307 Physics - STUDY HELP FOR FINAL

Final Exam Review in PDF

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Pearls of Wisdom

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UNIT CF Ext D - Important info

1) When balanced forces act on an object at rest, it will remain at rest. 2) When balanced forces act on a moving object, it will continue moving at a constant speed. 3) When a single force acts on an object in the same direction as its motion, it will speed up. 4) When a single force acts on an object in the opposite direction to its motion, it will slow down. 5) When an unbalanced combination of two forces acts on an object at rest, it will start to move in the direction of the strongest force. 6) When an unbalanced combination of forces acts on an object that is already moving, its speed will change.

Review Power Point 2 Newton's three laws of motion

1. Every object will remain at rest or in uniform motion in a straight line unless compelled to change its state by the action of an external force. a. When forces are balanced, speed and direction remain constant. 2. The acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object. a. F=ma OR change in speed=Net force/mass 3. For every action (force) in nature there is an equal and opposite reaction. In other words, if object A exerts a force on object B, then object B also exerts an equal and opposite force on object A. a. When you hit the wall, the wall hits you back

Review Power Point 3 Unit L Lesson 3

1. How can we describe the behavior of light when it enters and leaves transparent materials? Snell's Law(simplified): When a light ray passes: ➢ From air into a transparent material and the light ray crosses the normal line it bends slightly toward the normal line ➢ From a transparent material into air between 0° and about 50°, the light ray crosses the normal line it bends slightly away from the normal line. Greater than 50°, the light bounces back into the material. ➢ Between mediums at 0°, it does not bend.

Review PowerPoint 3 Unit EM Lesson 7

1. How can we keep track of amounts of energy as it flows through a system of interacting objects (including the surroundings)? **this equation... efficiency (in%) = amount of energy output via useful interaction/amount of decrease in stored (potential) energy x100 (pg 10 of slides) ➢ Calculate the efficiency ○ Sample problems next slide ➢ Solve for missing value ○ (conservation of energy)

Review PowerPoint 3 Unit EM Lesson 6

1. How can we trace the flow of energy through a system of interacting objects (including the surroundings)? **

Review PowerPoint 3 Unit L Lesson 4 R=red G=green Y=yellow B=blue M=magenta C=cyan R+G+B=all colors W=white

1. How do we see color lights? ●Colored Lights (Addition) vs. Colored gels (Subtraction) 2. How do we see color objects? R+G = Y R + B = M G + B = C R+G+B = W (pg 5)

Review Power Point 3 Unit L Lesson 2

1. How does light reflect from shiny and non-shiny surfaces? (direct vs diffuse reflection) **(DIRECT) If the bundle of light rays is incident upon a smooth surface, then the light rays reflect and remain concentrated in a bundle upon leaving the surface. (DIFFUSE) On the other hand, if the surface is microscopically rough, the light rays will reflect and diffuse in many different directions. 2. How do you see an image in a flat mirror? **An image is said to be virtual when the reflected rays instead of meeting actually appear to meet and an image is said to be real when reflected rays actually meet. The image formed on a flat or a plane mirror is said to be virtual because the reflected rays instead of meeting actually appear to meet.

Review PowerPoint 3 Unit EM Lesson 5

1. What other interactions can change the temperature of objects? i. Heat Interactions ● Conduction, Convection, Infrared) pgs.EM 60-61 **While conduction is the transfer of heat energy by direct contact, convection is the movement of heat by actual motion of matter; radiation is the transfer of energy with the help of electromagnetic waves. ii. Expanding energy diagrams ● Add "Surroundings" iii. Expanding Conservation Statements

Recorded stuff from Exam 2 lesson

Net is from the larger force when it's a bigger and smaller force Constant is no force added/acting or forces are balanced Gravitational force is always going to be pointing downward when we are on planet Earth (when a hand is pushing something upwards against the gravitational force, the hand has to have a greater force to push upwards) F=ma formula Net force is adding up the numbers in one direction and subtracting the numbers in the other direction .... Do algebra where you balance equations on both sides Having more friction than force means slow down, having more force than friction means speed up Evidence is what do you see happening...explain it in a way a child would understand it , answer them through the lens of a future elementary school teacher Balanced forces (If two individual forces are of equal magnitude and opposite direction, then the forces are said to be balanced. - opposite and equal...like a ball on a rope.) and unbalanced forces (When two forces acting on an object are not equal in size, we say that they are unbalanced forces - tug a war.) Balance is constant speed, unbalanced is change in speed

Recorded stuff from Exam 1 lesson

No north south entities to align when a nail is plastic Magnetism electrons never transfer they are just aligned, in static electricity electrons can transfer Protons never move for anything Models should be revised or changed whenever they don't match the current data Can't see the tiny magnets inside a magnet - not evidence An uncharged object and a charged object always attract (just like opposites with magnets)

(UNIT M, Ext A) - When standing in my home in California, if the red portion of my compass needle points south (toward Mexico) that means: a. The compass is working correctly. The polarity has not flipped. b. The compass has flipped polarity. The red portion should be pointing north (toward Canada). c. All compasses are different so there is not enough information given.

Week 1, Wednesday The correct answer is: The compass has flipped polarity. The red portion should be pointing north (toward Canada).

SE Ext E - Which of the following is most appropriate to describe what happens when a person discharges a negatively (-) charged object by touching it? Select one: a. Positive charges pass from the person to the object. b. Negative charges pass from the person to the object. c. Positive charges pass from the object to the person. d. Negative charges pass from the object to the person.

Week 4, Wednesday Your answer is incorrect. The correct answer is: Negative charges pass from the object to the person.

Recorded stuff from Exam 3 lesson

Use straight edge to draw lines for picture ones (like the pinhole) If you move a light source closer to the blocker the shadow will get bigger (the closer it gets)...when moving the screen closer to the blocker it will also get bigger Light goes in every direction (with a pinhole, the only light that matters is the one that makes it through the pinhole) Non shiny surfaces have multiple light rays out, shiny surfaces like a mirror have one light ray out Color gels are color subtraction *filters out a primary color* (red, green and blue are primary colors and all colors) Energy is never created or destroyed, energy is just transferred from one form to another Efficiency calculation - Eff%=attended(desire)/the whole x 100 If something gets warmer it has to increase in Thermal Energy (TE) meaning it has to take it from somewhere ... *you can't give cold to something* When something that is in motion is receiving energy it will get faster Constant means no energy transferred Types of interactions: heat, light, contact push/pull, sound or electric circuit Light moves in a straight line with a pinhole the angle that the light hits it will effect which light goes through since light goes in multiple different directions, this angle will change the position on the other side of the card that has the pinhole Shadow can be larger because blocking more of the light (the light rays are blocked) light travels in straight lines, the shadow is never smaller than the blocker because all the other light rays that aren't blocked will go past it White card is a non shiny surface so one light ray goes in an multiple go out Mirror is shiny surface so one light ray goes in and one light ray goes out Conservation statement is for example "Decrease in Chemical Potential energy = the Increase in Thermal Energy of the surroundings + the Increase in Light receivers" all in boxes and so on...

(UNIT M, Ext A) - Which of the following statements best explains why the North Pole of a compass needle points (approximately) toward the geographic North Pole of the Earth? Select one: a. The North Pole of the imaginary large bar magnet inside the Earth lies close to the geographic North Pole. (Magnetic north is geographic north.) b. The South Pole of the imaginary large bar magnet inside the Earth lies close to the geographic North Pole. (Magnetic south is geographic north.)

Week 1, Wednesday The correct answer is: The South Pole of the imaginary large bar magnet inside the Earth lies close to the geographic North Pole. (Magnetic south is geographic north.)

(UNIT M, Ext A) - Below are images of three positions of a compass near a bar magnet. The pointed end of the compass needle represents its North Pole. Only one of these three images shows the best approximation of the orientation of the compass needle, the other two are incorrect. Which image is correct? Select one: a. Image A b. Image B c. Image C

Week 1, Wednesday The correct answer is: Image B

(UNIT M, Ext A) - What kinds of materials are attracted to a magnet/can be magnetized? (Only magnetized items will cause a compass to react.) a. All materials- both metals and non-metals b. Only metals, not non-metals c. Only certain metals, not all metals. Not non-metals. d. Only non-metals, not metals. e. Certain metals and certain non-metals but not all of them.

Week 1, Wednesday The correct answer is: Only certain metals, not all metals. Not non-metals.

(UNIT M, Ext A) - Below is an image of a bar magnet, with its Poles indicated. Imagine a compass were placed at position X and then at position Y. Which direction would the North Pole of the compass point at each position? (Yes, you MUST watch/do the Extension first or you may "guess" wrong!) Select one: a. The North Pole of the compass (red tip) would point to the right at position X and to the right at position Y. b. The North Pole of the compass (red tip) would point to the right at position X and to the left at position Y. c. The North Pole of the compass (red tip) would point to the left at position X and to the right at position Y. d. The North Pole of the compass (red tip) would point to the left at position X and to the left at position Y.

Week 1, Wednesday The correct answer is: The North Pole of the compass (red tip) would point to the right at position X and to the right at position Y.

UNIT L Ext A - Shadows will always have the same general shape as the blocker that formed them Select one: True False

Week 10, Monday The correct answer is 'True'.

UNIT L Ext A - Below is a setup of an extended source a certain distance from a pinhole. The screen is the same distance on the other side of the pinhole. The screen shows a sharp upside down image of the source. Now imagine that the distance between the source and pinhole is doubled and the distance between the screen and pinhole is halved (one-half as much). If that were done, what would happen to the size of the image on the screen? Select one: a. It would be about the same size. b. It would be much larger. c. It would be much smaller.

Week 10, Monday Your answer is correct. The correct answer is: It would be much smaller.

UNIT L Ext A - To the right is a particular arrangement of a point source, a rectangular-shaped blocker and a screen. The shadow region is shown on the front view of the screen. Imagine that the blocker were moved to the right, closer to the screen. Assume the positions of the light source and screen remained unchanged. What would happen to the shadow region on the screen? Select one: a. It would become smaller. b. It would become larger. c. It would remain the same size.

Week 10, Monday Your answer is correct. The correct answer is: It would become smaller.

UNIT L Ext A - Below is a side view diagram of a light source, blocker and screen, and also a front view of the screen. A shadow is formed and is drawn on the front view of the screen. What will happen to the size of the shadow, compared to its original size, if the source were moved three quarters of the way towards the blocker and the screen were also moved one-fourth the way to the blocker, as shown by the dashed arrows on the side view diagram? [Hint: You should sketch a light ray diagram for the new positions and compare the size of the shadow region to the original size.] Select one: a. The shadow would be larger in size. b. The shadow would be about the same size. c. The shadow would become smaller in size.

Week 10, Monday Your answer is incorrect. The correct answer is: The shadow would be larger in size.

UNIT L Ext A - When drawing a light ray diagram which of the following do you need to account for? (Select all that apply) a. Light must travel FROM the light source TO the receiver (arrow should point away from light) b. Light must travel TO the light source FROM the receiver (arrow should point toward the light) c. Light only travels in straight lines d. Light rays that are blocked in someway will not illuminate on the screen (those areas will be dark)

Week 10, Monday Your answer is partially correct. You have correctly selected 2. The correct answers are: Light only travels in straight lines, Light must travel FROM the light source TO the receiver (arrow should point away from light), Light rays that are blocked in someway will not illuminate on the screen (those areas will be dark)

LESSON L Ext B - Below are three different arrangements of two mirrors near a source of light. For each arrangement, a light ray is drawn from the source to the first mirror. In which of these arrangements would the light eventually travel parallel to, but in the opposite direction to, the original light. [This type of device is called a retro-reflector.] Select one: a. Arrangement A b. Arrangement B c. Arrangement C

Week 10, Wednesday Your answer is correct. Completing the ray diagrams for each option should indicate that arrangement B is the best choice. This arrangement, in which the two mirrors are at a 90 degree angle (also called a right angle) to one another, is the standard arrangement for a retro-reflector. The correct answer is: Arrangement B

LESSON L Ext B - A cyclist has a helmet with a mirror attached that she uses to see objects behind her. Which of the following light ray diagrams correctly shows how light behaves so she can see the headlight of a car behind her? Select one: Diagram A Diagram B Diagram C Diagram D

Week 10, Wednesday Your answer is correct. The correct answer is: Diagram D

LESSON L Ext B - The light ray diagram below is supposed to show a person looking at a white book that he is holding in his hand. There is a black-colored barrier blocking light from the lamp from directly going to the book. The ceiling is a large mirrored surface. What is wrong with this light ray diagram? Select one: a. The light striking the ceiling should reflect in more than one direction, rather than in the one direction as shown. b. The light striking the book should only reflect in one direction, rather than in the many directions as shown. c. Light reflecting from the book should also be shown entering the eye. d. A and B only are wrong. e. A and C only are wrong.

Week 10, Wednesday Your answer is correct. The correct answer is: Light reflecting from the book should also be shown entering the eye.

LESSON L Ext B - How does the angle of incidence compare to the angle of reflection? a. The angle of incidence is equal to the angle of reflection b. The angle of incidence is greater than the angle of reflection c. The angle of incidence is less than the angle of reflection d. The angle of incidence is not comparable to the angle of reflection

Week 10, Wednesday Your answer is correct. The correct answer is: The angle of incidence is equal to the angle of reflection

LESSON L Ext B - Thinking back to the activity on Reflection of light and the mirror and white card on the table. If you were to add another person on either side of the table along with the 2 people pictured here, what would they see? a. The mirror and white card will both appear dark. b. The mirror will be bright and shiny and the white card will be bright white. c. The mirror will be bright and shiny, but the white card will appear dark d. The mirror will appear dark, but the white card will appear bright white.

Week 10, Wednesday Your answer is incorrect. The correct answer is: The mirror will appear dark, but the white card will appear bright white.

LESSON L Ext B - What happens when light strikes a white or non shiny surface? a. Light reflects from white card in one direction, the same way that it reflects from a mirror. b. Light reflects from the white card in many directions, quite different from the way it reflects from a mirror c. Light does not actually reflect from the white card; it just spreads out on the card and illuminates it. d. Light will not reflect off a non shiny surface

Week 10, Wednesday Your answer is incorrect. The correct answer is: Light reflects from the white card in many directions, quite different from the way it reflects from a mirror

UNIT EM Ext A - During a lesson, you are asked to respond to the following three statements. Statement #1: How do you think the speed-time graph would change if you gave it a harder push? Statement #2: Record the speed-time graph after the instructor gives the car a push. Statement #3: Why are the slopes of the two portions of the speed-time graph different? Which of these statements are asking you to make an observation, make an inference, or make a prediction? Select one: a. Statement #1 is an observation, #2 is an inference and #3 is a prediction. b. Statement #1 is an inference, #2 is an observation and #3 is a prediction. c. Statement #1 is a prediction, #2 is an observation and #3 is an inference. d. Statement #1 is a prediction, #2 is an inference and #3 is an observation.

Week 12, Monday The correct answer is: Statement #1 is a prediction, #2 is an observation and #3 is an inference.

UNIT EM Ext A - Below is the speed-time graph for an object that can move in either direction along a track. Which of the following statements could best match the speed-time graph? Select one: a. The object first speeds up at a certain rate, then speeds up at a lower rate, and finally speeds up at a higher rate than it initially sped up. b. The object speeds up at a certain rate, then slows down at an even greater rate to a momentary stop, changes direction, and finally speeds up again at the same rate as it initially sped up. c. The object speeds up at a certain rate, then slows down at a lower rate to a momentary stop, changes direction, and finally speeds up at a higher rate than it initially sped up. d. The object speeds up at a certain rate, then slows down at a lower rate to a momentary stop, changes direction, and finally speeds up again at the same rate as it initially sped up.

Week 12, Monday The correct answer is: The object speeds up at a certain rate, then slows down at a lower rate to a momentary stop, changes direction, and finally speeds up again at the same rate as it initially sped up.

UNIT EM Ext A - During a contact push/pull interaction________________ (Select all that apply) a. 2 (or more) objects are in contact b. the speed of one or both objects will change speed during the interaction c. energy is transferred between 2 (or more) objects d. both objects must be moving after the interaction

Week 12, Monday The correct answers are: 2 (or more) objects are in contact, the speed of one or both objects will change speed during the interaction, energy is transferred between 2 (or more) objects

UNIT EM Ext A - Think about the text and the icons that were explained in the Extension Activity that are used throughout the lessons. Why is it important for teachers to articulate these types of symbols and their meaning to the students? (Choose all that apply) a. If you draw attention to the symbols, the students might be more receptive to the cues they provide. b. Students generally thrive with consistency so showing them some of the tools embedded in their texts can be helpful. c. Not all students will notice them if teachers do not point them out. Taking a few minutes at the beginning of a term may help the students more effectively utilize the tools available. d. Some students like to pre-read and/or skim so showing them the specific cues provided by a given text may help them to focus on key points. e. Teachers don't need to point them out. The students will figure them out.

Week 12, Monday The correct answers are: If you draw attention to the symbols, the students might be more receptive to the cues they provide., Students generally thrive with consistency so showing them some of the tools embedded in their texts can be helpful., Not all students will notice them if teachers do not point them out. Taking a few minutes at the beginning of a term may help the students more effectively utilize the tools available., Some students like to pre-read and/or skim so showing them the specific cues provided by a given text may help them to focus on key points.

UNIT EM Ext A - Consider the following scenario. A car speeds up from rest, then travels at a constant speed, then speeds up again, but at a slower rate than at first. Then the car slams on its brakes, slowing down at a rate greater than the rates of speeding up. Which of the following speed-time graphs most reasonably matches this description of the car's motion? Select one: a. Choice A b. Choice B c. Choice C d. Choice D

Week 12, Monday The correct answer is: Choice A

EM, Ext E - When thinking about forces and energy it is important to remember that ENERGY transfers during an interaction but FORCE never transfers. Select one: True False

Week 12, Wednesday The correct answer is 'True'.

EM Ext D - A block is observed to slide across the table, slowing down to a stop. Which one of the following G/R energy diagrams might plausibly describe the interaction between the block and table? (TE = thermal energy; KE = kinetic energy) Select one: Choice A Choice C Choice D Choice B

Week 12, Wednesday Your answer is correct. The correct answer is: Choice A

EM, Ext E - For these questions consider a new situation associated with the child pushing the toy car across the carpet. Toward the end of the scenario, while still in contact with both the hand and the carpet, the toy car decreased in speed and stopped. Note that during this period the car and the carpet continued to get warmer because friction was still affecting them. Which of these G/R energy diagrams would be most appropriate for this situation? Select one: a. Choice C b. Choice B c. Choice A

Week 12, Wednesday Your answer is correct. The correct answer is: Choice C

EM Ext D - Which of the following provides evidence that the thermal energy of an object is decreasing? Select one: a. Its speed is increasing. b. Its temperature is increasing. c. Its speed is decreasing. d. Its temperature is decreasing.

Week 12, Wednesday Your answer is correct. The correct answer is: Its temperature is decreasing.

SE, Ext B - Below are images and descriptions of three different arrangements of charges from the 'Electric Field Hockey' simulation. Which one of these would result in a goal being scored when the positively-charged puck is released? (Please note the charges present at each position on the simulation when pondering your answer.) Select one: a. Arrangement A b. Arrangement B c. Arrangement C

Week 3, Wednesday Your answer is correct. The correct answer is: Arrangement C

EM Ext D - A chair is pushed across the floor, and then let go. The chair comes to a very quick stop. A previous student wrote an explanation narrative for why the chair slows down after being let go. Read her evaluation, and then evaluate it for accuracy. (1) There is a contact push/pull interaction between the chair and floor. (2) During the interaction, energy is transferred from the chair to the floor. (3) The kinetic energy of the chair decreases while its thermal energy increases, as well as the thermal energy of the floor. (4) Because the thermal energy of the chair increases, it slows down. This explanation is: Select one: a. Not accurate because sentence #3 is not correct. b. Not accurate because sentence #1 is not correct. c. Not accurate because sentence #4 is not correct. d. Not accurate because sentence #2 is not correct. e. Accurate as written.

Week 12, Wednesday Your answer is correct. The correct answer is: Not accurate because sentence #4 is not correct.

EM, Ext E - While the speed of the toy car was decreasing, what can you say about the tendency of the two interactions involved? Select one: a. The tendency of interaction with the hand to increase the speed (kinetic energy) of the cart was stronger than the tendency of the interaction with the carpet to decrease its speed (kinetic energy). b. The tendency of interaction with the hand to increase the speed (kinetic energy) of the cart was equal to the tendency of the interaction with the carpet to decrease its speed (kinetic energy). c. The tendency of interaction with the hand to increase the speed (kinetic energy) of the cart was weaker than the tendency of the interaction with the carpet to decrease its speed (kinetic energy).

Week 12, Wednesday Your answer is correct. The correct answer is: The tendency of interaction with the hand to increase the speed (kinetic energy) of the cart was weaker than the tendency of the interaction with the carpet to decrease its speed (kinetic energy).

UNIT EM, Ext C - Consider two carts moving along a track. Cart 1 is moving much more quickly than cart 2. Both carts 1 and 2 have some clay attached to their ends. Cart 1 catches up to cart 2 and collides with it. They stick together and the two carts move to the right at a speed in between the initial speeds of carts 1 and 2. Which of the following is the complete evidence that the two carts were involved in a contact push/pull interaction? Select one: a. Cart 1 slowed down and cart 2 speeded up. b. The two carts touched each other and they changed their speed as a result of the collision. c. The two carts pushed and pulled against each other. d. The two carts touched each other.

Week 12, Wednesday Your answer is correct. The correct answer is: The two carts touched each other and they changed their speed as a result of the collision.

EM, Ext E - When working with energy transfer and interaction diagrams: (Select all that apply) a. There can be multiple types of interactions within the same interaction series (contact push/pull, thermal, etc.) b. Energy must be in the same form throughout the interaction (ONLY kinetic or ONLY CPE, etc) c. There CANNOT be multiple types of interactions within the same interaction series (contact push/pull, thermal, etc.) d. It is possible to have multiple energy receivers. e. It is possible to have multiple energy givers. f. Energy can take multiple forms in the same diagram (kinetic, chemical potential, etc.)

Week 12, Wednesday Your answer is correct. The correct answers are: It is possible to have multiple energy givers., It is possible to have multiple energy receivers., Energy can take multiple forms in the same diagram (kinetic, chemical potential, etc.), There can be multiple types of interactions within the same interaction series (contact push/pull, thermal, etc.)

UNIT EM, Ext C - Which one of the following G/R energy diagrams best describes the interaction between the two carts in the previous problem? Select one: a. Choice B b. Choice D c. Choice C d. Choice A

Week 12, Wednesday Your answer is incorrect. The correct answer is: Choice D

UNIT EM, Ext C - Consider the following energy diagram and and an accompanying written narrative for what happens when someone's hand pushes a cart to get it to start moving. Written narrative: When a person's hand pushes the cart to start it moving, there is a contact push/pull interaction between the hand and the cart. Energy is transferred from the hand to the the cart, and the cart increases in kinetic energy. Because the cart's kinetic energy increases, it starts moving. Which assumption of the energy model is NOT reflected in either the energy diagram or the written narrative? Select one: a. During an interaction, energy can be transferred between objects. b. Energy cannot be created or destroyed, only transferred between objects, or transformed to different types within the same object. c. From any change in an observable property we can infer a change in the corresponding type of energy. d. Certain observable properties of an object can be associated with different types of energy.

Week 12, Wednesday Your answer is incorrect. The correct answer is: Energy cannot be created or destroyed, only transferred between objects, or transformed to different types within the same object.

UNIT EM, Ext C - In working with energy diagrams, why do we only include diagrams for the period of time DURING the interaction(s)? a. Energy cannot be created or destroyed, only transferred between objects, or transformed to different types of energy within the same object. b. Energy is only transferred during the interaction. Before and after the interaction, there is no energy transfer so nothing "changes" during those periods. c. The energy transfer is the same during all periods so additional diagrams would be redundant. d. We do not have data from before or after the interaction so we cannot produce an appropriate diagram.

Week 12, Wednesday Your answer is incorrect. The correct answer is: Energy is only transferred during the interaction. Before and after the interaction, there is no energy transfer so nothing "changes" during those periods.

EM Ext D - Which of the following provides evidence that the KINETIC energy of an object is decreasing? a. Its speed is increasing. b. Its speed is constant. c. Its temperature is decreasing. d. Its speed is decreasing.

Week 12, Wednesday Your answer is incorrect. The correct answer is: Its speed is decreasing.

EM, Ext E - When addressing energy and interactions and constructing appropriate diagrams, there are instances where the energy of a particular energy component does not change. (As shown in the extension.) For these situations, you would ____________________________. a. Omit the portion of the interaction (show no increase or decrease in that particular type of energy). b. Show the increase and decrease of that particular type of energy. c. This never occurs so this question is irrelevant.

Week 12, Wednesday Your answer is incorrect. The correct answer is: Omit the portion of the interaction (show no increase or decrease in that particular type of energy).

EM Ext D - When objects slow/stop, where does the energy go? (Answer all that are plausible.) a. The energy is transformed within the object from kinetic energy to another type of energy (like thermal energy.) b. The energy disappears. c. The energy transfers into another object. The other object then increases in some type of energy. d. The energy goes into the surroundings. The energy of the surroundings increases.

Week 12, Wednesday Your answer is partially correct. You have correctly selected 2. The correct answers are: The energy transfers into another object. The other object then increases in some type of energy., The energy goes into the surroundings. The energy of the surroundings increases., The energy is transformed within the object from kinetic energy to another type of energy (like thermal energy.)

UNIT EM, Ext C - Suppose a soccer player kicks the soccer ball. Which one of the following G/R energy diagrams would best describe the interaction between the soccer player and the soccer ball? Select one: a. Choice A b. Choice C c. Choice B d. Choice D

Week 12, Wednesday Your answer is correct. The correct answer is: Choice B

UNIT EM, Ext G - Suppose a cup of hot chocolate is sitting on a table. A woman puts her hand close to the cup on its right side, but not touching (as in the image). Nonetheless, her hand begins feeling a bit warmer. When she grasps the cups, she feels her hand warming up even more rapidly. The energy diagrams below demonstrate the mechanisms involved in making her hand warmer. (Note that these diagrams are incomplete, because both the cup and hand also transfer energy to the surroundings through heat interactions. These interactions are not shown because they are not needed for answering this question.) Now consider the primary mechanism(s) behind the first interaction and energy transfer (left diagram). Which of the following best explains why her hand begins to feel warmer before she touched the cup? Select one: a. Charged particles in the hot chocolate and the cup vibrate more rapidly than the charged particles in her hand, emitting higher-intensity infrared radiation than her hand does, so that the hand absorbs more IR radiation than it emits. b. Vibrating molecules in the hot chocolate move faster than the vibrating molecules in her hand, producing a wave of energy that travels through the air and is absorbed by her hand. c. Collisions between high-speed, vibrating molecules in the hot chocolate and the cup generate more infrared radiation than collisions between the (relatively) low-speed molecules in her hand, so that the hand absorbs more IR radiation than it emits. d. Collisions between particles in the hot chocolate and the cup with air particles transfer energy to the air particles, causing the air near the cup to warm up. Interacting with the cool air around it, the warm air rises upward through the cool air until it touches the hand. Collisions between air and hand particles then cause the hand to warm up.

Week 13, Monday The correct answer is: Charged particles in the hot chocolate and the cup vibrate more rapidly than the charged particles in her hand, emitting higher-intensity infrared radiation than her hand does, so that the hand absorbs more IR radiation than it emits.

UNIT EM, Ext G - If you were designing a room in a house, where would be the better place to put a heater, near the floor or near the ceiling? Why? Consider your answer in the context of convection. Select one: a. Near the ceiling, because the air warmed by the heater would quickly spread down and across the room, replacing the cold air. b. Near the floor, because the heater would warm the air close to it. After being heated, the now-warm air would rise, and be replaced by cool air, which the heater would warm. The cycle would continue until the room is heated. c. Near the ceiling, because the heater would warm the air close to it. After being heated, the now-warm air would descend, and be replaced by cool air, which the heater would warm. The cycle would continue until the room is heated. d. Near the floor, because the air warmed by the heater would quickly spread up and across the room, replacing the cold air.

Week 13, Monday The correct answer is: Near the floor, because the heater would warm the air close to it. After being heated, the now-warm air would rise, and be replaced by cool air, which the heater would warm. The cycle would continue until the room is heated.

UNIT EM, Ext G - As you saw in the first part of this homework, at the microscopic level heat conduction is a chain of collisions by particles of different kinetic energies. Suppose a heat interaction occurs between a hot object of 80 °C and a cool object of 10 °C, and the primary energy transfer mechanism is heat conduction. If the interaction continues for an extended period of time, how will the average kinetic energy of the particles in the (initially) hot object compare to the average kinetic energy of the particles in the (initially) cool object? Select one: a. The average KE of the hot object particles will be greater than the average KE of the cool object particles. b. The average KE of the hot object particles will be smaller than the average KE of the cool object particles. c. The average KE of the hot object particles will be the same as the average KE of the cool object particles. d. There is no way to determine the correct answer.

Week 13, Monday The correct answer is: The average KE of the hot object particles will be the same as the average KE of the cool object particles.

UNIT EM, Ext G - When thinking about three thermal interactions discussed in the lesson and in the extension (conduction, convection, and IR), ________________________________ ALWAYS occurs in conjunction with at least one other type of heat interaction. a. conduction b. convection c. IR d. All three types ALWAYS work in conjunction.

Week 13, Monday The correct answer is: convection

UNIT EM, Ext G - "Heat Interactions" is the general term used whenever the primary mechanism for thermal energy transfer is conduction, convection, and/or IR. For the G/R diagrams, the general term is used because ________________________. a. more than one type of these heat interactions is often involved when thermal energy changes. b. differentiating between the individual interactions is tedious and a waste of time. c. conduction and convection are essentially the same process.

Week 13, Monday The correct answer is: more than one type of these heat interactions is often involved when thermal energy changes.

EM, Ext F - Consider the case of the hockey player and the puck, but this time consider what happens while the player is using his muscles to swing his hockey stick before it hits the puck. Evaluate the following explanation for why the hockey stick speeds up as it gets closer to the puck. (You should draw your own G/R energy diagram on a separate sheet before reading the explanation.) (1) As the player swings the hockey stick towards the puck, there is a contact push/pull interaction between the player and the stick. (2) During this interaction, energy is transferred from the hockey player to the stick, the player decreases his chemical potential energy, and the kinetic energy of the hockey stick increases. (3) Because the kinetic energy increases, the hockey stick speeds up as it gets closer to the puck. This explanation is: Select one: a. Inaccurate because sentence #1 is incorrect. b. Inaccurate because more than one sentence is incorrect. c. Accurate as written. d. Inaccurate because sentence #3 is incorrect.

Week 13, Monday Your answer is correct. The correct answer is: Accurate as written.

SE, Ext D - Suppose you had a positively (+) charged object that you wanted to make uncharged. Which would be the easiest way to do so? Select one: a. Remove some protons from it. b. Add some electrons to it. c. Both A and B would be equally easy.

Week 4, Monday Your answer is correct. The correct answer is: Add some electrons to it.

EM, Ext F - A previous student wrote the following explanation for how 'brake fade' occurs. Evaluate this explanation for accuracy. (1) When the brake pedal is pushed down, there is a friction-type contact push/pull interaction between the brake pads and the wheels. (2) As a result, energy is transferred from brake pads to the wheels. (3) The thermal energy of the brake pads increases. (4) The kinetic energy of the wheels decreases and their thermal energy increases. (5) As the thermal energy of the brake pads increase, they get very hot and the pad surface wears out; this is what causes 'brake fade.' Which explanation is best? Select one: a. Accurate as written. b. Inaccurate because more than one sentence is incorrect. c. Inaccurate because sentence #2 is incorrect. d. Inaccurate because sentence #1 is incorrect. e. Inaccurate because sentence #3 is incorrect.

Week 13, Monday Your answer is correct. The correct answer is: Inaccurate because sentence #2 is incorrect.

EM, Ext F - When working with energy and interactions, generally "muscles" is a huge clue that ______________________________ energy is decreasing in the person. a. kinetic b. force c. chemical potential d. thermal

Week 13, Monday Your answer is correct. The correct answer is: chemical potential

EM, Ext F - Generally when working with interactions, _________________ energy is directly related to speed and _____________________energy is directly related to temperature. kinetic, thermal motion, force potential, kinetic light, sound thermal, kinetic

Week 13, Monday Your answer is correct. The correct answer is: kinetic, thermal

EM, Ext F - When you apply the brakes on a bicycle, pads of rubber are pushed against the metal rims of the wheels to slow them down via a friction-type contact push/pull interaction between them. One of the problems that can occur with bicycle brakes is that of 'brake fade', which is the loss of the brakes' ability to stop the bicycle. (This usually happens with prolonged heavy use of the brakes, such as when descending a steep hill.) Which of the following G/R energy diagrams best describes the interaction between the brake pads and the wheels? Hint: When answering this question, consider only the energy transfer. What object(s) loses energy (overall), the wheel or the brake pads? What gains energy? What does that imply about the direction of the energy transfer arrow? Select one: a. Choice B b. Choice A c. Choice D d. Choice C

Week 13, Monday Your answer is incorrect. The correct answer is: Choice D

UNIT EM, Ext H - According the the scenario and diagram: The energy input to the heat pump from the power plant is equal to the energy output from the heat pump to the surroundings due to heat interactions. Select one: True False

Week 13, Wednesday The correct answer is 'False'.

UNIT EM, Ext H - According to the scenario and diagram: The energy input to the heat pump from the cooling soda due to heat interactions is equal to the energy output from the heat pump to the surroundings due to heat interactions. Select one: True False

Week 13, Wednesday The correct answer is 'False'.

UNIT EM, Ext H - According to the scenario and diagram: The sum of the energy inputs to the heat pump from the power plant and from the cooling soda in the fridge is equal to the sum of the thermal energy increase in the surroundings and the energy increase in the sound receivers. Select one: True False

Week 13, Wednesday The correct answer is 'True'.

UNIT EM, Ext H - According to the the scenario and diagram: The sum of the energy inputs to the heat pump from the power plant and from the cooling soda in the fridge is equal to the sum of the energy outputs to the surroundings and to sound receivers. Select one: True False

Week 13, Wednesday The correct answer is 'True'.

UNIT EM, Ext H - Consider the scenario presented in the last question on the homework before the quiz. For the period of time when the heat pump is in dynamic equilibrium and the food is still cooling, which of the following statements on energy conservation in the refrigerator chain of reactions are true, and which are false? Use the energy diagram of the interaction chain (below) as a reference. #1= The thermal energy decrease in the soda is equal to the energy transferred from the soda to the heat pump. Select one: True False

Week 13, Wednesday The correct answer is 'True'.

UNIT M, Ext B - Now consider a group who found that, when they cut a magnetized nail into either halves or ¼ and ¾ pieces, the pieces of the magnetized nail still behaved as if they were two-ended. Description: Inside the nail, there are equal numbers of separate N and S magnetic particles that can move around when attracted or repelled by a magnet. In the unmagnetized nail, they are all jumbled up randomly. When the nail is rubbed with one pole of a bar magnet, the magnetic particles arrange themselves as shown in the diagram. (The - represents S) BASED ON THIS MODEL, Which of the following observations could NOT be explained using this model? (Choose all that apply.) Select one or more: a. The magnetized nail behaves like a two-ended (bar) magnet. b. Cutting the nail anywhere along its length produces two pieces that each behave like two-ended magnets. c. Each end of the magnetized nail can pick up the same number of paper clips. d. When cut in half, each end of each half of the nail (four ends in all) can pick up the same number of paper clips. e. After dropping the magnetized nail in water and removing it, the wet nail is still magnetized.

Week 2, Monday The correct answer is: Cutting the nail anywhere along its length produces two pieces that each behave like two-ended magnets.

UNIT M, Ext B - This group's model is similar to the last group's model. In this case, the group performed experiments in which they cut a number of magnetized nails into two pieces of various lengths and found that both pieces were always two-ended. Here is their model for the magnetized nail: Description: Inside the nail there are equal numbers of separate N and S magnetic particles that can move around when attracted or repelled by a magnet. In the unmagnetized nail, these N and S particles are all jumbled up randomly. When the nail is rubbed with one pole of a bar magnet, the magnetic particles arrange themselves alternately along the length of the nail. (The - represents S) Could THIS MODEL be used to explain the observation that when a magnetized nail is cut into two pieces of arbitrary lengths both pieces are always two-ended? Select one: a. Yes, according to the model diagram, anywhere the nail is cut would produce two pieces that are both two-ended. b. No, according to the diagram, there are some places where the nail could be cut and the two pieces produced would not be two-ended.

Week 2, Monday The correct answer is: No, according to the diagram, there are some places where the nail could be cut and the two pieces produced would not be two-ended.

UNIT M, Ext B - Consider the model from a different group, similar to but not the same as Group 2's model from the extension activity: Description: There are no magnetic entities associated with the unmagnetized nail, but when a magnet is rubbed along the surface of the nail, it deposits small N and S entities (like dust particles) loosely along the surface, as shown. (The - represents S) BASED ON THIS MODEL, Which of the following observations made by some other groups could NOT be explained/justified using this model? (Choose all that apply.) Select one or more: a. The magnetized nail behaves like a two-ended (bar) magnet. b. Cutting the magnetized nail in half produces two pieces that each behave like two-ended magnets. c. Cutting the nail anywhere along its length produces two pieces that each behave like two-ended magnets. d. Each end of the magnetized nail can pick up the same number of paper clips. e. When cut in half, each end of each half of the nail (four ends in all) can pick up the same number of paper clips. f. After dropping the magnetized nail in water and removing it, the wet nail is still magnetized.

Week 2, Monday The correct answers are: Cutting the nail anywhere along its length produces two pieces that each behave like two-ended magnets., When cut in half, each end of each half of the nail (four ends in all) can pick up the same number of paper clips., After dropping the magnetized nail in water and removing it, the wet nail is still magnetized.

UNIT M, Ext B - The Magnetism unit lessons and extensions rely heavily on modeling. Modeling can be very useful. When using models I MUST remember: (Choose all that apply) a. Models should be reevaluated and possibly updated when new information/data is gathered. b. Models can never change once they have been established. c. A model must be able to explain all of the observations that have been made so far. d. The model may be able to explain all of the observations/data but still not show what is actually occurring. e. None of the above

Week 2, Monday The correct answers are: Models should be reevaluated and possibly updated when new information/data is gathered., A model must be able to explain all of the observations that have been made so far., The model may be able to explain all of the observations/data but still not show what is actually occurring.

UNIT M, Ext B - Modeling is especially useful for students when: (Choose all that apply.) a. The entities are either too small or too large to be actually observed. b. Students want to understand any "invisible" phenomena in a physical or visual way but do not have the ability to otherwise. c. Teachers are working with students to help them understand how to process and interpret data. d. Teachers are working with students to help them understand the importance of the scientific method and how it can be used without an actual laboratory setting.

Week 2, Monday The correct answers are: The entities are either too small or too large to be actually observed., Students want to understand any "invisible" phenomena in a physical or visual way but do not have the ability to otherwise., Teachers are working with students to help them understand how to process and interpret data., Teachers are working with students to help them understand the importance of the scientific method and how it can be used without an actual laboratory setting.

SE Ext, A - Based on what you know and what you have learned so far (think about the triboelectric series) please answer the following: You have probably experienced the phenomenon of 'static cling', particularly when taking your laundry out of the dryer. A student dries three separate loads of laundry as described in the choices below. For which load (if any) are they most likely to notice a large amount of 'static cling'? a. A load consisting of only cotton materials. b. A load consisting of a mixture of cotton and nylon materials. c. A load consisting of only nylon materials. d. All of these loads (A, B, and C) will produce a large amount of 'static cling'.

Week 3, Wednesday The correct answer is: A load consisting of a mixture of cotton and nylon materials.

SE Ext, A - In the extension activity, you constructed a simple triboelectric series for the three materials in the simulation (diamond, circle and square). According to the simulation evidence, which one of the choices below is the correct order for how they should be placed in this series? (Yes, you need to watch the extension and the simulator activities BEFORE attempting the quiz!) A '1' is for the material most likely to be positively (+) charged, a '2' is equally likely to be either positively (+) or negatively (-) charged, and a '3' is most likely to be negatively (-) charged. (If you are unsure, in another tab, open and watch the simulation again before answering). Select one: a. (1) Square; (2) Diamond; (3) Circle. b. (1) Square; (2) Circle; (3) Diamond. c. (1) Diamond; (2) Square; (3) Circle. d. (1) Diamond; (2) Circle; (3) Square. e. (1) Circle; (2) Diamond; (3) Square.

Week 3, Wednesday The correct answer is: (1) Square; (2) Circle; (3) Diamond.

SE Ext, A - Earlier in the unit you determined that when an acrylic sheet is rubbed with a Styrofoam plate (which is a brand name for polystyrene), the acrylic becomes positively (+) charged and the Styrofoam becomes negatively (-) charged. From this information where should acrylic be placed in the triboelectric series shown here? Select one: a. Somewhere above polystyrene b. Somewhere below polystyrene c. It is impossible to say with this information.

Week 3, Wednesday The correct answer is: Somewhere above polystyrene

SE Ext, A - According to the triboelectric series shown here, what would happen if Vinyl were rubbed on Teflon? (Remember, the items on the top are most likely to become positively charged in an interaction while those at the bottom are most likely to become negatively charged in an interaction.) Select one: a. Both the Vinyl and the Teflon would become negatively (-) charged. b. The Vinyl would become positively (+) charged and the Teflon would become negatively (-) charged. c. The Teflon would become positively (+) charged and the Vinyl would become negatively (-) charged. d. Both the Vinyl and the Teflon would become positively (+) charged.

Week 3, Wednesday The correct answer is: The Vinyl would become positively (+) charged and the Teflon would become negatively (-) charged.

SE, Ext B - What kinds of materials can be involved in static electric effects? a. All types of materials, both metals and non metals b. Only metals but not non-metals c. Only non metals but not metals d. Only certain metals but not all metals and not non-metals e. Only certain metals and certain non-metals

Week 3, Wednesday Your answer is correct. The correct answer is: All types of materials, both metals and non metals

UNIT FM Ext B - According to the simulator graphs, the more force that was exerted __________________ a. the less the skateboarder changed speed b. the more constant the speed of the skateboarder became c. the smaller the force graph d. the greater the change in speed of the skateboarder

Week 6, Wednesday The correct answer is: the greater the change in speed of the skateboarder

SE, Ext B - What happens when two objects are charged by rubbing or peeling? a. One object has only one type of charge. The other object has only the other type of charge. b. Both objects have the same type of charge. c. Both objects have both types of charge, but there are different amounts of each type on each object. (One object has more negative charges than positive and the other object has more positive charges than negative charges.)

Week 3, Wednesday Your answer is correct. The correct answer is: Both objects have both types of charge, but there are different amounts of each type on each object. (One object has more negative charges than positive and the other object has more positive charges than negative charges.)

SE, Ext B - The arrangement below from the 'Electric Field Hockey' simulator shows a negatively (-) charged puck in front of the goal. Directly behind the goal is a line of three charges (-, +, -), with a second + charge directly behind the first. How would the negatively-charged puck behave when it is released, and why? (If you are unsure, I encourage you to revisit the simulator in another tab before answering.) Select one: a. It would be attracted toward the goal because the + charges are both in the middle of the arrangement. b. It would not move toward or away from the goal because there are equal numbers of + and - charges behind the goal. c. It would repelled away from the goal because taken together, the two negative charges are nearer to it than the two positive charges.

Week 3, Wednesday Your answer is incorrect. The correct answer is: It would repelled away from the goal because taken together, the two negative charges are nearer to it than the two positive charges.

SE, Ext B - When you bring a small object close to a charged tape you find that there is an attraction between them. Considering all the evidence you saw early in this unit, what can you conclude about the charge of the small object? Select one: a. It has the same charge as the tape. b. It is uncharged. c. It has the opposite charge to the tape. d. Either B or C could be true.

Week 3, Wednesday Your answer is partially correct. The correct answer is: Either B or C could be true.

SE Ext, A - BEFORE any static interaction, such as rubbing, all objects tend to be _____________________. a. neutral/ uncharged b. positively charged c. negatively charged d. either positively or negatively charged

Week 3, Wednesday The correct answer is: neutral/ uncharged

SE Ext C - Based on the videos and supplies used, it is clear that science must always be done with materials that are expensive and difficult to obtain. Select one: True False

Week 4, Monday The correct answer is 'False'.

SE Ext C - In another class, a student drew a diagram and gave a written explanation for what happens when a negatively-charged Styrofoam plate is brought near a soda can electroscope. Student's Model: Student's explanation: Before the plate is brought close to the base end of the soda can electroscope, the positive and negative charges are uniformly distributed in the soda can and the tinsel, and both ends of the soda can are uncharged. When the negatively (-) charged Styrofoam plate is brought next to the electroscope, all of the positive charges in the soda can (and the tinsel) move toward the negatively charged plate because of the Law of Electric Charges, which states that opposite charges attract. All of the negatively charged particles move toward the tinsel end, and into the tinsel, because like charges repel. For that reason, the negatively-charged pieces of tinsel repel each other. Evaluate the student's model. Can the diagram and the written explanation account for the evidence presented in the experiment and simulation movies that you watched in this extension? (This question is not asking if this is a correct account. This question is asking about whether the account addresses the evidence. Evidence and data are all part of the modeling process. You need to know how to relate the phenomena to the data and evidence not only to prior knowledge.) Select one: a. Both the diagram and the written explanation can account for the evidence provided by the movies. b. The diagram can account for the evidence provided by the movies, but the written explanation cannot. c. The written evidence can account for the evidence provided by the movies, but the diagram cannot. d. Neither the diagram nor the written explanation can account the evidence provided by the movies.

Week 4, Monday The correct answer is: Both the diagram and the written explanation can account for the evidence provided by the movies.

SE Ext C - Based on the lesson and extension, evaluate the following: Static electric effects are different when objects touch as compared to the interactions when they are simply brought near (but to not touch) each other. a. This statement is true. While both touching and bringing near can result in attraction and/or repulsion, touching seems to last longer. b. This statement is false. Touching and proximity exhibit the same static effects of attraction and repulsion. c. The statement is misleading. Both touching and proximity result in the same phenomena of attraction and/or repulsion. Touching appears to last longer while proximity effects only last while the objects are near one another. d. There is not enough information given to evaluate the statement.

Week 4, Monday The correct answer is: The statement is misleading. Both touching and proximity result in the same phenomena of attraction and/or repulsion. Touching appears to last longer while proximity effects only last while the objects are near one another.

SE Ext C - Which of the following pieces of evidence should lead the student to change her model (either the diagram, the written explanation, or both)? (She should only change the model if her current model does not support the "new" evidence.) Choose all answers that apply. Select one or more: a. Evidence or separate knowledge that only one type of charge (either + or -) can actually move in the electroscope, rather than both types (+ and -) of charges moving. b. Evidence that a positively-charged object attracts the tinsel, when the negatively-charged plate is held close to the electroscope's base side. c. Evidence or separate knowledge that the middle portion of the soda can (between the top and base) is uncharged when the negatively-charged plate is held near the base end. d. Evidence or separate knowledge that, while both types of charges can move, they can only move a very short distance in the soda can. e. Evidence that a negatively-charged object repels the tinsel (pushes the tinsel strands together), when the negatively-charged Styrofoam plate is being held close to the electroscope's base side.

Week 4, Monday The correct answers are: Evidence or separate knowledge that only one type of charge (either + or -) can actually move in the electroscope, rather than both types (+ and -) of charges moving., Evidence or separate knowledge that, while both types of charges can move, they can only move a very short distance in the soda can.

SE, Ext D - Given what you have learned in this extension, which of the following would be the most appropriate assumption to make in a model that uses charged entities to explain static electric effects? Select one: a. Positively (+) charged entities can move through materials and be transferred to other objects, but negatively (-) charged entities cannot move b. Negatively (-) charged entities can move through materials and be transferred to other objects, but positively (+) charged entities cannot move. c. Both negatively (-) and positively (+) charged entities can move through materials and be transferred to other objects.

Week 4, Monday Your answer is correct. The correct answer is: Negatively (-) charged entities can move through materials and be transferred to other objects, but positively (+) charged entities cannot move.

SE, Ext D - According to the reasoning you applied in the second part of this assignment, when the Styrofoam plate and acrylic sheet have been rubbed together, how does the acrylic sheet acquire a positive charge? Select one: a. The Styrofoam plate transfers positive (+) charges to the acrylic sheet. b. Positive (+) charges are created on the acrylic sheet. c. Negative (-) charges are destroyed on the acrylic sheet. d. The acrylic sheet transfers negative (-) charges to the Styrofoam plate. e. Some combination of A, B, C, and D occurs.

Week 4, Monday Your answer is correct. The correct answer is: The acrylic sheet transfers negative (-) charges to the Styrofoam plate.

SE, Ext D - Uncharged objects have ____________________________ entities on or within them. a. no charged b. equal quantities of positively (+) and negatively (-) charged c. unequal quantities of positively (+) and negatively (-) charged

Week 4, Monday Your answer is correct. The correct answer is: equal quantities of positively (+) and negatively (-) charged

SE Ext C - Based on your observations from the lesson and extension, you have hopefully realized the entities responsible for overall charge reside on the surface of the object. Which piece of evidence MOST supports this conclusion? (Yes, all of these statements are true based on your observations. The question is asking which one best supports the conclusion about the charges being on the surface.) a. A charged object that is touched on the surface, or submerged in water, becomes uncharged. b. Uncharged objects are ALWAYS attracted to charged objects. c. The triboelectric series can be used to determine the most likely charge an object will exhibit when charged by rubbing or contact with another object on the series. d. An uncharged object can be charged by touch or proximity with a charged object.

Week 4, Monday The correct answer is: A charged object that is touched on the surface, or submerged in water, becomes uncharged.

SE Ext F - When an object is "Polarized" in terms of charge, different regions of the object will have different charges, thus the object is 2 ended with respect to charge. Select one: True False

Week 4, Wednesday The correct answer is 'True'.

SE Ext F - Consider the following situation. Suppose a - charged object were placed above an uncharged non-metal object. Which of the diagrams shown and described below would best represent the polarization of the atoms in the non-metal object? (Yes, you need to go through the extension activity before you should attempt this quiz.) Select one: a. Choice A b. Choice B c. Choice C

Week 4, Wednesday The correct answer is: Choice B

SE Ext F - If you rub a balloon against your hair, the balloon becomes negatively charged. If you then hold the rubbed part of the balloon against a wall and let go, assuming the conditions are not too humid, the balloon will stay 'attached' to the wall, at least for a short while. Suppose this is the arrangement of charges on the balloon and the wall before the negatively charged balloon touches the wall. For simplicity, for the balloon, we are only showing the excess negative charges on the surface that was rubbed. Which one of the following four diagrams would most accurately represent how the charges in the wall are arranged after the balloon comes into contact with the wall? Select one: a. Choice A b. Choice B c. Choice C d. Choice D

Week 4, Wednesday The correct answer is: Choice B

SE Ext F - A plastic strip is held near a piece of tape and an ATTRACTION is observed. What do you KNOW from this single observation? a. The tape is charged. b. The straw is charged. c. Either the tape, or the straw, or both are charged. d. The tape and straw both have the same type of charge. e. The tape and straw have opposite types of charge. (This is not the best answer. Please read carefully.)

Week 4, Wednesday The correct answer is: Either the tape, or the straw, or both are charged.

SE Ext F - When dealing with phenomena like Static Electric Interactions, why is the type of material significant to know when making predictions? a. The (-) entities are more free to move in metals than in nonmetals so the behavior can be somewhat different. b. The (+) entities move more freely in metals which makes them more reactive. c. The type of material is not important for making predictions.

Week 4, Wednesday The correct answer is: The (-) entities are more free to move in metals than in nonmetals so the behavior can be somewhat different.

SE Ext E - Conductors are different from insulators in that______________________ a. in an insulator, the negative charges are completely stuck in place. You can neither add nor take away negative charges. b. in an insulator, the negative charges cannot move as freely as in a conductor. For insulators, charges are generally only transferred from the point of contact not the entire object. c. They are not different. d. all non metals are insulators.

Week 4, Wednesday Your answer is correct. The correct answer is: in an insulator, the negative charges cannot move as freely as in a conductor. For insulators, charges are generally only transferred from the point of contact not the entire object.

SE Ext E - You have likely experienced a static 'shock' after walking across a carpet, just as John Travoltage did in the simulator. Which of the following best explains why this is much more likely to happen on a cold, dry, winter's day than a warm, humid, summer's day? Select one: a. Humid air does not undergo 'breakdown' so the charges do not transfer to the doorknob until you touch it. b. Negative charges are transferred to you from the carpet on a cold day, but not on a warm day. c. Negative charges are transferred to you from the carpet on both warm and cold days, but these excess negative charges do not remain on you. Instead, they are removed almost immediately by humid air.

Week 4, Wednesday Your answer is incorrect. The correct answer is: Negative charges are transferred to you from the carpet on both warm and cold days, but these excess negative charges do not remain on you. Instead, they are removed almost immediately by humid air.

SE Ext E - Which of the following is most appropriate to describe what happens when a person discharges a positively (+) charged object by touching it? Select one: a. Positive charges pass from the person to the object. b. Negative charges pass from the person to the object. c. Positive charges pass from the object to the person. d. Negative charges pass from the object to the person.

Week 4, Wednesday Your answer is incorrect. The correct answer is: Negative charges pass from the person to the object.

SE Ext E - Particles responsible an object being charged or uncharged (protons and electrons) cannot be created or destroyed. Select one: True False

Week 4, Wednesday The correct answer is 'True'.

UNIT FM Ext A - Here are the force diagrams for two carts being pushed forward as they move along separate tracks. (Please remember to differentiate between force arrows and motion arrows when considering your diagrams.) Based on the information in the diagrams, which of these two carts is moving faster? Select one: a. Cart A b. Cart B c. Both are moving at the same speed d. It is impossible to tell

Week 6, Monday Cart A is moving faster because it has the longer speed arrow. Because a stronger force is being exerted on Cart B, Cart B may eventually end up moving faster, but it isn't moving faster at the time represented by the force diagrams. The correct answer is: Cart A

UNIT FM Ext A - While arguing over who owns a toy, two children, Cindy and Scott, both grab it and engage in a 'tug-of-war' over it. At one certain moment in time during their struggle, the force diagram for the toy looks like this. Which of the following statements best describes what this force diagram represents? Select one: a. Scott is pulling harder than Cindy, and the toy is moving toward him at this particular moment in time. b. Cindy is pulling harder than Scott, and the toy is moving toward her at this particular moment in time. c. Cindy is not pulling as hard as Scott, but the toy is moving toward her at this particular moment in time. d. At this particular moment in time Scott and Cindy are pulling equally hard, so the toy is not moving.

Week 6, Monday Choice C (Cindy is not pulling as hard as Scott, but the toy is moving toward her at this particular moment in time.) is the only one that fits with the diagram. The length of the force arrows indicates that Scott is pulling harder than Cindy. However, the speed arrow indicates the toy is moving toward Cindy. The correct answer is: Cindy is not pulling as hard as Scott, but the toy is moving toward her at this particular moment in time.

UNIT FM Ext A - A moving cart is given a push by someone's hand so that a force is exerted on it. The force diagram for a moment in time while this force is acting is shown here. (Please remember to differentiate between force arrows and motion arrows when considering your diagrams.) Several seconds later it is observed that the cart is still moving, but measurements show that the force of the hand is no longer acting on the cart. Which of the force diagrams below would be most appropriate for the cart at this later moment in time? Select one: a. Choice A b. Choice B c. Choice C

Week 6, Monday Force diagram B is the only diagram that fits with the description—that the cart is moving but that the force of the hand is no longer acting on it. Remember, a force diagram represents the forces acting on, and the motion of, an object at a particular moment in time. It does not show forces, or motion, that happened in the past, or will happen in the future. The correct answer is: Choice B

UNIT FM Ext A - A child's sled is sliding across a frozen lake toward a patch of thin ice. To try and prevent this, you lasso the sled and pull on the rope in the opposite direction to its motion to try and slow it down. Which of the diagrams below would best represent this situation, assuming it is for a moment in time before you successfully brought the sled to a stop? (Look carefully at the placement and direction of the arrows.) Select one: a. Choice A b. Choice B c. Choice C

Week 6, Monday Force diagram C best represents this situation. It shows a pulling force acting on the sled in the opposite direction to its speed arrow. Diagrams A and B show a force acting in the same direction as the sled's motion! The correct answer is: Choice C

UNIT FM Ext A - When working with force diagrams, the single headed arrow indicates _______________. a. the direction of the force exerted b. the relative magnitude of the force being exerted c. the relative magnitude and direction of the force being exerted d. the direction and relative speed the object is traveling in

Week 6, Monday The correct answer is: the direction and relative speed the object is traveling in

UNIT FM Ext B - Based on the graphs for the extensions, I noticed the speed of the skateboarder only changed when a force was being exerted. Select one: True False

Week 6, Wednesday A force is required to change the motion of an object. The correct answer is 'True'.

UNIT FM Ext C - For the purposes of this class, kinetic energy is the energy an object has due to its speed at a given time. Select one: True False

Week 6, Wednesday The correct answer is 'True'.

UNIT FM Ext B - Shown here is a force diagram for the skateboarder in this assignment at a time of 6 seconds after the simulator started (halfway through the period during which he was being pushed). Which of the force diagrams below would be most appropriate for him at a time of 10 seconds (well after the push has ended, assuming friction is minimal)? Select one: a. Choice A b. Choice B c. Choice C

Week 6, Wednesday The correct answer is: Choice C

UNIT FM Ext B - Suppose you are watching an ice-hockey game with some classmates. As the puck is sliding across the ice at a relatively constant speed, it passes close to a player, who hits it (with his stick) in the same direction as it is already moving. After the hit, you notice that the puck is moving much faster than it was before the hit. Your classmates propose the following three explanations for why the puck is moving faster after the hit than before. Whose reasoning do you agree with? Student A:"The force of the stick was transferred to the puck during the hit. After the hit, the puck has more force, so it moves faster." Student B: "The puck still has the force that started it moving, which is what keeps it moving at a constant speed. When the player hit sit, he adds to this force, which makes the speed of the puck increase. After the hit, this extra force is gone, so the puck stops increasing in speed, but the original force is still there so now it moves at a faster constant speed." Student C: "While the stick is in contact, it applies a force to the puck that makes its speed increase. As soon as contact is lost, this force is no longer present, so the speed of the puck stops increasing." Select one: a. Student A b. Student B c. Student C

Week 6, Wednesday The correct answer is: Student C

UNIT FM Ext C - Here is a force diagram for a cart at a particular moment in time. Assuming the same force continues to act, how will this cart's kinetic energy in a few seconds compare with its kinetic energy now, and why? (Think about what we have discussed about the evidence for kinetic energy. What does more or less kinetic energy "look" like?) Select one: a. Its kinetic energy will be the same because the force stays the same. b. It will have less kinetic energy because the force will slow it down. c. Its kinetic energy will be the same because no energy is being transferred to it. d. It will have more kinetic energy because energy is being transferred to it.

Week 6, Wednesday Your answer is correct. The correct answer is: It will have more kinetic energy because energy is being transferred to it.

UNIT FM Ext C - Shown below are the speed-time and force-time graphs from a simulator. Which of these statements is consistent with what the graphs show is happening to the simulator cart at t = 9 seconds? Select one: a. Its kinetic energy is increasing and no force is acting on it. b. Its kinetic energy is constant and no force is acting on it. c. Its kinetic energy is increasing and a force is acting on it. d. Its kinetic energy is decreasing and a force is acting on it.

Week 6, Wednesday Your answer is correct. The correct answer is: Its kinetic energy is constant and no force is acting on it.

UNIT FM Ext C - When referring to the cart being pushed by the hand, an interaction___________________________ a. occurs before, during, and after the contact b. occurs only DURING the period of time when they hand and cart are in contact c. occurs before and after the contact between the hand and the cart d. results in constant speed while they are in contact

Week 6, Wednesday Your answer is correct. The correct answer is: occurs only DURING the period of time when they hand and cart are in contact

UNIT FM Ext C - Force and energy _______________________________ a. are different in that force is NOT transferred during an interaction b. are related in that energy is transferred while a force is being exerted c. are interchangeable concepts

Week 6, Wednesday Your answer is partially correct. You have correctly selected 1. The correct answers are: are different in that force is NOT transferred during an interaction, are related in that energy is transferred while a force is being exerted

UNIT FM Ext B - You may want to watch the movie again for the first two questions. Here is the URL for the movie:https://www.youtube.com/watch?v=GqSPuLZlQTQ Shown here is a force diagram for the skateboarder in this assignment at a time of 6 seconds after the simulator started (halfway through the period during which he was being pushed). Which of the force diagrams below would be most appropriate for him at a time of 2 seconds (well before the push started)? Select one: a. Choice A b. Choice B c. Choice C

Week 6, Wednesday The correct answer is: Choice B

UNIT FM Ext E - An object in motion will continue to travel in a straight line unless an opposing force acts. The opposing force can be a sideways force, a backwards force, or some other type of force that is not acting in the same direction as the current motion. Select one: True False

Week 7, Monday The correct answer is 'True'.

UNIT FM Ext D - Thinking about the previous question with the sticky notes, if the bumps on the sandpaper were very small compared to the barriers created by the sticky notes, what do you think is the most likely reason that the frictional force produced by the sandpaper stopped the block more quickly than the sticky notes? Select one: a. There was about the same number of backwards taps in each case, but each bump in the sandpaper produced a slightly stronger backwards tap than each sticky note. b. There were fewer bumps in the sandpaper than there were sticky notes, but each bump produced a much stronger backwards tap than each sticky note. c. The backward tap produced by each bump in the sandpaper was weaker than that produced by each sticky note, but the number of bumps in the sandpaper was much higher than the number of sticky notes that were used.

Week 7, Monday Your answer is correct. The correct answer is: The backward tap produced by each bump in the sandpaper was weaker than that produced by each sticky note, but the number of bumps in the sandpaper was much higher than the number of sticky notes that were used.

UNIT FM Ext D - Air resistance is a specific type of ____________________ a. drag force b. water resistance c. vacuum force d. interaction

Week 7, Monday Your answer is correct. Air resistance is a frictional force exerted on an object as it travels through the air. Drag force is a more general term as other things like liquids or other gases can exert a frictional force as well. The correct answer is: drag force

UNIT FM Ext E - Imagine tying a stuffed toy to a string and swinging it around in a horizontal circle above your head at a constant speed. The picture shows a top view at a particular moment in time, with the curved arrow simply indicating the direction of rotation. Four dashed arrows (labeled A, B, C, D) point away from the toy at this position. Which of these would be most appropriate to show the direction of the force acting on the toy at this particular moment in time? (For this one, remember that force is different from motion. Think about the direction the STRING is exerting the force on the toy.) Select one: a. Arrow A b. Arrow B c. Arrow C d. Arrow D

Week 7, Monday Your answer is correct. The correct answer is: Arrow D

UNIT FM Ext D - Some students were comparing their ideas about how friction works with a demonstration they saw in an earlier lesson, in which several very gentle 'backward' taps were applied to a moving cart, thereby slowing it down in several 'steps'. One student made the following statement: "When we slowed the cart down in Lesson 4, we were applying several weak 'backward' forces to it. Each one of these forces made the cart slow down a little, until eventually it stopped. But friction is different, there are no backward forces acting on the block, it's just the rubbing on the surface that makes it slow down. " How do this student's ideas compare to your own thinking? Select one: a. I agree with this student. The two processes are very different from each other. b. I disagree with this student. There are backward forces acting on an object when it slides across a surface that are very like the backwards taps applied to a cart by someone's hand just on a different scale.

Week 7, Monday Your answer is correct. The correct answer is: I disagree with this student. There are backward forces acting on an object when it slides across a surface that are very like the backwards taps applied to a cart by someone's hand just on a different scale.

UNIT FM Ext E - If no sideways forces act on a moving object, what will its path be like? Select one: a. It will move in a zigzag pattern. b. It will move in a straight line. c. It will move in a circular path.

Week 7, Monday Your answer is correct. The correct answer is: It will move in a straight line.

UNIT FM Ext E - Now, suppose, after the toy has moved a bit further round the circle, the string were to break when the toy was in the position shown in this diagram. Which of the dashed arrows best indicates the path the toy would follow after the string breaks? (This question is asking about motion NOT force. Please read each question carefully before finalizing your answer.) Select one: a. Path A b. Path B c. Path C d. Path D

Week 7, Monday Your answer is correct. The correct answer is: Path C

UNIT FM Ext D - In many situations studied in physics, the effect of the drag force is ignored. Such situations would include the carts moving along the tracks that you have seen presented in class. Why can the drag force be neglected in such situations? Select one: a. The experiments were done in a vacuum, so no air was present. b. The speeds of the carts were low enough that the drag forces acting on them were very weak. c. The carts are small enough that there would be no drag force acting on them, no matter how fast they were moving.

Week 7, Monday Your answer is correct. The correct answer is: The speeds of the carts were low enough that the drag forces acting on them were very weak.

UNIT FM Ext E - When a 'sideways' force acts on a moving object, what effect does it have? Select one: a. It makes the object's speed increase. b. It makes the object's speed decrease. c. It changes the direction that the object is moving. d. It has no effect on the object's motion.

Week 7, Monday Your answer is incorrect. The correct answer is: It changes the direction that the object is moving.

UNIT FM Ext D - You may have been using an analogy between a row of sticky notes and the sandpaper surface to develop your ideas about how a frictional force is produced when a block slides across sandpaper. However, you have seen that even when the block slides across an apparently smooth tabletop, it still slows down. Consider how our analogy might be extended to explain how a frictional force is produced when the block slides across an apparently smooth surface. What do you think you would see if you looked at a smooth tabletop with a powerful magnifier? Select one: a. A thin layer of moisture on the surface that makes it somewhat 'sticky'. b. Very small bumps and grooves in the surface. c. Nothing. It would still look perfectly smooth.

Week 7, Monday Your answer is correct. The correct answer is: Very small bumps and grooves in the surface.

UNIT CF Ext B - After completing the first part of this homework assignment, Luisa made this comment: Which of the following statements best addresses Luisa's concern? Select one: a. Luisa is correct. An object with balanced forces cannot be moving. b. Another push is needed to start such an object moving, and during that push, the forces are unbalanced. c. Another push is needed to start such an object moving, but during that push, the forces are still balanced.

Week 8, Monday Your answer is correct. If the object is in motion, there must have been a force exerted at some point in time to change the speed for the object from rest. The correct answer is: Another push is needed to start such an object moving, and during that push, the forces are unbalanced.

UNIT CF Ext A - Frank and Hector are moving two boxes across a rough floor. Frank pushes a 20 kg box with a force of 85 N while a frictional force of 75 N acts on it in the opposite direction. Meanwhile, Hector pushes on the 30 kg box with a force of 105 N while a frictional force of unknown strength acts on it. (Hint: calculate for Frank first and that will help you know the acceleration for Hector. Use that information to calculate the net force for Hector.) Frank and Hector find that as their boxes are moving, they remain side-by-side, so they realize they must both be changing speed at the same rate. What is the strength of the frictional force acting on the 30 kg box? Select one: a. 95 N b. 93 N c. 75 N d. 90 N

Week 8, Monday Your answer is correct. The correct answer is: 90 N

UNIT CF Ext B - If an object's motion is changing, what must be true? a. No energy is being transferred into or out of the object. b. The net sum of all forces must be zero. c. An outside force (or multiple forces) must be acting.

Week 8, Monday Your answer is correct. The correct answer is: An outside force (or multiple forces) must be acting.

UNIT CF Ext B - This question again refers to the demonstration you previously saw that was referred to in the last question. Assuming the speed of the cart is indeed constant, which one of these force diagrams is the most appropriate for the cart just after the initial push? Select one: Choice A Choice C Choice B

Week 8, Monday Your answer is correct. The correct answer is: Choice A

UNIT CF Ext B - Previously, you saw a demonstration (or a movie of one) involving a cart that had two fan units pushing on it in opposite directions with equal strength. With the cart initially at rest, it was given a push to start it moving. Here is the force diagram for that cart when it is at rest. Which one of these force diagrams is the most appropriate for the cart at a moment during the short period it is getting the push that starts it moving? Select one: Choice C Choice B Choice A

Week 8, Monday Your answer is correct. The correct answer is: Choice C

UNIT CF Ext A - Two skateboarders start themselves moving at the same speed side-by-side. After their initial pushes, they slow down gradually due to the frictional force acting on each of them. The masses of the skateboarders and the strengths of the frictional forces are shown in the force diagrams below. Assuming they are initially moving at the same speed, which of the skateboarders will slow to a stop first, and why? (Hint: Think carefully about whether the first one to stop will have a higher or lower rate of change in his speed. As always, change of speed is the "a" in F=ma.) Select one: a. Skateboarder 1 will stop first because there is a stronger force acting opposite his motion. b. Skateboarder 1 will stop first because he has more mass. c. Skateboarder 1 will stop first because the quantity force strength/mass is lower for him. d. Skateboarder 2 will stop first because the quantity force strength/mass is higher for him.

Week 8, Monday Your answer is correct. The correct answer is: Skateboarder 2 will stop first because the quantity force strength/mass is higher for him.

UNIT CF Ext D - As the elevator passes the second floor, it starts to slow down so that it can stop at the first floor. While it is slowing down as it descends, how would the forces acting on the elevator compare? Select one: a. The upward force of the cable would be stronger than the downward gravitational force. b. The upward force of the cable would be weaker than the downward gravitational force. c. The upward force of the cable would be equal in strength to the downward gravitational force.

Week 8, Wednesday Your answer is correct. The correct answer is: The upward force of the cable would be stronger than the downward gravitational force.

UNIT CF Ext A - At the beginning of this extension activity, we asked how we could tell which of the two boxes below would speed up at the higher rate. The ideas you have developed in this assignment should help you decide the answer to this question. (Hint: simplify to net force before doing your F=ma calculation.) Which of these two boxes will speed up at a higher rate, and why? Select one: a. The 35 kg box will speed up at a higher rate because the quantity net force strength/mass is greater for this box. b. The 35 kg box will speed up at a higher rate because it has less mass. c. The 50 kg box will speed up at a higher rate because the quantity net force strength/mass is greater for this box. d. The 50 kg box will speed up at a higher rate because the net force acting on it is stronger.

Week 8, Monday Your answer is correct. The correct answer is: The 35 kg box will speed up at a higher rate because the quantity net force strength/mass is greater for this box.

UNIT CF Ext B - After a hockey player gives a puck a quick 'hit' with his stick, the puck slides across the ice at a speed that is essentially constant. A student in a previous class offered the following force diagram and explanation for why the speed of the puck is constant after the hit. Please evaluate both the diagram and narrative for accuracy and completeness of ideas. "The initial hit exerts a force on the puck, making the forces acting on the puck unbalanced, and so it starts to move. After the hit ends there is no net force acting on the puck, and when the net force acting on an object is zero, its speed does not change. So after the stick has lost contact with the puck, its speed remains constant." What is your evaluation of this explanation? Select one: a. Both the force diagram and the narrative are problematic. b. The force diagram is problematic but the narrative is accurate. c. Both the force diagram and the narrative are accurate. d. The force diagram is accurate but the narrative is problematic.

Week 8, Monday Your answer is correct. The correct answer is: The force diagram is problematic but the narrative is accurate.

UNIT CF Ext A - When shopping for a new car, a professor was surprised to learn that a certain small compact car (mass=800 kg) will speed up (accelerate) at a faster rate than a large SUV (mass=2200 kg), although the SUV has the more powerful engine. What is the reason that the compact car can speed up at a faster rate than the SUV, despite having a less powerful engine? (Think in terms of Newton's second law please.) Select one: a. The quantity pushing force divided mass is smaller for the compact car. b. The quantity pushing force divided mass is greater for the compact car. c. The quantity pushing force times mass is smaller for the compact car. d. The quantity pushing force times mass is greater for the compact car.

Week 8, Monday Your answer is correct. The correct answer is: The quantity pushing force divided mass is greater for the compact car.

UNIT CF Ext A - Shown below are force diagrams for three carts that have different masses and are being pushed forward by different strength fans. If these three carts were in a race, which one would speed up at the slowest rate and hence lose the race? Select the cart that you think will finish last in a race between them. (Yes, you will need to use Newton's second law to calculate the acceleration for each to make the correct determination.) Select one: a. Choice B b. Choice C c. Choice A

Week 8, Monday Your answer is correct. The correct answer is: Choice C

UNIT CF Ext D - Imagine an empty elevator is making a trip down from the 10th floor to the 1st floor of a building. The following three questions concern various stages in this journey. The elevator starts at rest on the 10th floor and then starts to move downward, speeding up as it does so. While this is happening, how would the forces acting on the elevator compare? Select one: a. The upward force of the cable would be equal in strength to the downward gravitational force. b. The upward force of the cable would be stronger than the downward gravitational force. c. The upward force of the cable would be weaker than the downward gravitational force.

Week 8, Wednesday Your answer is correct. The correct answer is: The upward force of the cable would be weaker than the downward gravitational force.

UNIT CF Ext C - Several children of different ages and sizes are playing a "tug-of-war" game over a large box of toys. The force diagrams below indicate the forces that between one and four children are exerting on the box at different times. The friction force that the floor exerts on the box is also shown. In each case, the box is moving to the right (as indicated by the red speed arrow). In which example is the speed of the box not constant? (Look for the box that will be changing speed.) Select one: Choice A Choice B Choice C Choice D

Week 8, Wednesday Your answer is correct. The correct answer is: Choice C

UNIT CF Ext C - Consider the force diagrams for four low-friction carts shown below. Each cart is subject to pushes from two fans (not shown) mounted on opposite ends of the cart. The forces the fans exert of the carts are shown. All four carts are moving to the right (the speed arrows are not shown). In each case, the cart experiences a small friction force in the opposite direction to its motion. These friction forces are also shown. Each cart has a mass of 1 kg, but three of the carts also carry objects that contribute to their total mass. The total mass of each cart and the object it carries (if any) is indicated in the force diagrams below. Which cart experiences the greatest rate of change in speed? (Yes, you will need to use your math skills here!) Select one: Choice A Choice C Choice D Choice B

Week 8, Wednesday Your answer is correct. The correct answer is: Choice D

UNIT CF Ext D - You have seen that the effect of the drag force on a skydiver is to make him speed up at a slower and slower rate as he falls, until he reaches his terminal velocity. Which of the speed-time graphs below shows this behavior? Select one: a. Graph A b. Graph B c. Graph C

Week 8, Wednesday Your answer is correct. The correct answer is: Graph A

UNIT CF Ext D - As it passes the 9th floor, the elevator reaches the desired descent speed and so travels from here down to the 2nd floor at a constant speed. While it is moving downward at a constant speed, how would the forces acting on the elevator compare? Select one: a. The upward force of the cable would be stronger than the downward gravitational force. b. The upward force of the cable would be weaker than the downward gravitational force. c. The upward force of the cable would be equal in strength to the downward gravitational force.

Week 8, Wednesday Your answer is correct. The correct answer is: The upward force of the cable would be equal in strength to the downward gravitational force.

UNIT CF Ext C - Friction always _________________________ a. is constant b. is difficult to measure or observe when it is acting c. causes an object to change direction d. opposes motion

Week 8, Wednesday Your answer is correct. The correct answer is: opposes motion

UNIT CF Ext C - In order to reduce the force needed to move furniture in your home, you might consider: a. I cannot reduce the force needed to move the object. b. Reducing the friction between the object and the floor. c. Push upwards on the object instead of forward. d. Reducing the mass of the item by removing parts (pillows, drawers, etc.)

Week 8, Wednesday Your answer is partially correct. You have correctly selected 1. The correct answers are: Reducing the mass of the item by removing parts (pillows, drawers, etc.), Reducing the friction between the object and the floor.

UNIT CF Ext C - In a question Extension C, you considered the situation of moving a couch at a constant speed. You concluded that to move the couch at a constant speed, you would need to push it with a force that exactly balances the frictional force of 50 N acting on the couch. Now consider a situation in which the couch is at rest. You push on the couch with a force of 25 N. Unfortunately the couch still does not move. Which one of the force diagrams below best describes this situation? Select one: Choice A Choice C Choice B

Week 8, Wednesday Your answer is correct. There is NO change in speed so there must be a net force of zero. The correct answer is: Choice C

Review PowerPoint 2 Unit CF Lessons 1 through 2

● Combinations of forces a. How do objects behave when more than one force acts on them? i. Balanced vs. Unbalanced combinations of forces ii. What effect do combinations of forces have on an object that is already moving? b. Calculating NET force **F = ma, where F is the net force, m is mass and a is acceleration. ● Balanced Forces c. What is an object's motion like when a balanced combination of forces acts on it? iii. Newton's First Law: When the forces acting on an object are balanced, its speed (and direction) will remain constant. ● (If an object's speed is changing, an outside force must be acting.)

Review PowerPoint 1 Extra notes

● Compare and contrast Magnetic and Static interactions ● Analyze diagram for magnet and static electricity ideas ● How might you present this idea in your K-8 classroom? ● Touch, near, attract, repel- these actions are different and may change the answer or outcome.

Review PowerPoint 1 - Unit M, Lessons 1 through 2

● Developing a Model a. How can you decide whether a model is good or not? i. Must be supported by current data ● Exploring Magnetic Effects a. What are some properties of magnetic interactions? i. Poles (attraction, repulsion) **North attracts South and vice versa, North repels North, South repels South** ii. North Pole on a compass is an actual North Pole so it is South seeking. (Compasses North arrow is pointing to the North Pole because Santa lives at the Geographic north which is the magnetic South pole.) iii. Law of Magnetic Poles **The most basic law of magnetism is that like poles repel one another and unlike poles attract each other; this can easily be seen by attempting to place like poles of two magnets together.**

Review PowerPoint 1 - Unit M Lessons 3 through 4

● Developing a model for Magnetism a. How can you develop a model for magnetism? i. Collect data & observations ● Better Model for Magnetism a. How can you develop a better model for magnetism? i. Magnetic fields-alignment of particles ii. Orientation of particles iii. NS cannot be separated only realigned iv. NS are on the inside of the material

Review PowerPoint 1 - Unit M Lesson 5

● Explaining Phenomena Involving Magnetism a. How can you use the alignment model of magnetism to explain some phenomena? i. How to magnetize ferromagnetic materials. **the material can be magnetized (made into a magnet) by placing it in a magnetic field. When this happens, all the magnetic domains line up, and the material becomes a magnet.** ii. Magnetize with proximity and touch iii. Magnetic models iv. Magnetized with attract unmagnetized & Magnetized with attract opposite pole and repel same pole

Review PowerPoint 1 Unit SE Lesson 5

● Explaining Phenomena Involving Static Electricity a. How can you use the charges in materials model of static electricity to explain some phenomena? i. Protons (+) NEVER move ii. Electrons can transfer during contact ● Electrons (-) are more free to move within metals than nonmetals ● In metals they can actually travel within the substance, in non-metals they "lean" iii. Triboelectric series (look up picture of this if need to)

Review PowerPoint 1 Unit SE lessons 1 through 2

● Exploring Static Electric Effects a. What are some properties of interactions involving electrified objects? i. Types of materials ii. Attraction and repulsion, 2 types of charge ● Developing a model for Static Electricity a. How can you construct a model of static electricity and use it to explain your observations? i. Touching charged and uncharged items together ii. Charges on the surface

Review PowerPoint 2 Unit FM Lesson 6

● Falling Objects a. How does the mass of an object affect how it falls? b. How does mass affect the falling motion of objects? c. How does the strength of the gravitational force on an object depend on its mass? **More massive objects will only fall faster if there is an appreciable amount of air resistance present. ... Thus, the greater force on more massive objects is offset by the inverse influence of greater mass. Subsequently, all objects free fall at the same rate of acceleration, regardless of their mass.** i. The Earth exerts a ________ (DIFFERENT, same) strength gravitational force on objects with different masses. ii. The strength of the Earth's gravitational force is ______ (GREATER, weaker, the same) on a more massive object than on a less massive object. d. How can objects of different masses all fall at the same rate of increase in speed? **Objects that are said to be undergoing free fall, are not encountering a significant force of air resistance; they are falling under the sole influence of gravity. Under such conditions, all objects will fall with the same rate of acceleration, regardless of their mass.**

Review PowerPoint 2 Unit FM Lesson 4

● Forces and Friction ○ Is friction a force? a. If so, in what direction does it act? i. Friction ALWAYS OPPOSES motion ii. Yes, you will need to identify appropriate diagrams AND be able to do simple calculations involving forces (including friction.)

Review PowerPoint 3 Unit EM Lessons 1 through 2

● Interactions and Motion a. How is an object's motion affected by an interaction? i. Speed vs. time graphs graphs ii. Contact Push/Pull Interaction ● Motion and Energy b. What is needed (if anything) to change the kinetic energy of an object? iii. Energy Diagrams iv. Conservation of Energy & Energy Statement (this is concise management documents presenting the current understanding of a site, its significance and its conservation issues.)

Review PowerPoint 2 Unit FM Lesson 1

● Interactions, Force and Motion a. When does the force of a quick push stop acting on an object? b. When an object is moving, does this mean there must be a force pushing it in the direction of its motion? i. The interaction occurs only during the period when the hand and cart are in contact ii. Energy can be transferred, Force CANNOT be transferred. iii. You will need to be able to extrapolate a speed time graph from a force diagram iv. You will need to identify the correct force diagram based on the situation.

Review of PowerPoint 3 Items to remember for G/R diagrams and calculations

● Interactions-Contact push/pull, heat, electric circuit, light ● Energy types- Chemical potential, thermal, kinetic, "energy" ● Giver/ receiver examples- Cart, sun, person, batteries, generator, buzzer, heater, sound receivers, bulb, surroundings, fan, motor, solar cell, light receivers ● Efficiency calculation-Sample o 5000J of energy are transferred into a heater system. If 4000J are transferred to the surroundings as heat and 1000J are transferred as loud hum. What is the efficiency of the heater? o 300J of energy are transferred into a buzzer system. If 250J are used by the buzzer, how much energy is lost to the surroundings?

Review Power Point 3 Unit L Lesson 1

● Light Waves, Pinholes, and Shadows 1. What are light waves? **A light wave is an electromagnetic wave comprised of energy derived from oscillating magnetic and electric fields. Learn about the definition, uses, and types of light waves in the electromagnetic spectrum. ➢ Drawing and interpreting light ray diagrams 2. How do pinholes and shadows provide evidence that light travels in straight lines? **Shadows are evidence of light travelling in straight lines. ... Once light has hit another surface or particles, it is then absorbed, reflected (bounces off), scattered (bounces off in all directions), refracted (direction and speed changes) or transmitted (passes straight through). ➢ Explaining the size and shape of shadows

Review PowerPoint 2 Unit FM Lessons 2 through 3

● Motion with a Continuous Force a. How does an object move when a force of constant strength continuously pushes it forward? i. Newton's 1st Law tells us and object with changing speed MUST be experiencing an outside force. ● Pushes and Slowing Down b. What effect does a 'backward' push have on the motion of an object? **The generated in the backward direction gives an and opposite reaction in the forward direction. The more you push back the more you move forwards. Static friction while pushing an object: Sometimes when you apply a force nothing happens.** c. What happens if a continuous 'backward' push is applied to a moving object?

Review Power Point 2 Notes

● Read and interpret speed vs. time and force vs. time graphs ● Recognize appropriate force diagrams ● Calculating force or mass or acceleration (change in speed) ● How might you present this idea in your K-8 classroom? ● Before vs. during vs. after- these actions are different and may change the answer or outcome

Review PowerPoint 1 - Unit M Lesson 6

● Real World Application: Maglev Trains ● Teaching and Learning Science a. What does successful science instruction look like? **A good science lesson will encourage students to think critically and analyze evidence before making a conclusion about any particular problem. ... The lesson encourages students to base their conclusion on observations. The lesson does not facilitate the learning or use of science process skills.** b. NGSS & how to plan and implement ● Models, Magnets, and Children's ideas a. What are some ideas children have about magnetism and models? How magnets can be explained to kids: Magnetism is the force of attraction or repulsion between substances made of certain materials, such as iron, nickel, cobalt, and steel. The force of magnetism, simply put, is due to the motion of electric charges. Magnets are present in most electronic devices. In fact, anything that has a motor uses a magnet.

Review PowerPoint 1 Unit SE Lessons 3 through 4

● Representing Uncharged Objects in Your Model a. What is an appropriate way to represent uncharged objects in your model for static electricity? **Predictions, Observations and Making Sense** ● Refining Your Model for Different Materials a. How can you refine your model to account for the behavior of metals and non-metals? i. Charges are on the surface of items ii. Conductors and insulators **Conductors are materials that permit electrons to flow freely from particle to particle. ... Conductors allow for charge transfer through the free movement of electrons. In contrast to conductors, insulators are materials that impede the free flow of electrons from atom to atom and molecule to molecule.**

Review PowerPoint 2 Unit CF Lessons 3 and 4

● Situations involving friction a. How can we use our ideas about forces and motion to analyze situations involving friction? i. Constant speed vs. speeding up vs. slowing down (what does each situation indicate about the relative force of friction?) **If an object is moving at a constant speed the force of friction must equal the applied (horizontal) force, and for it to be accelerating or decelerating, the force of friction and the applied force must be unequal. (less friction than force for acceleration. more friction than force for deceleration). ● Comparing forces during interactions b. Newton's Third Law: When one object exerts a force on another, the second object exerts a force on the first that is equal in strength and in the opposite direction. c. Interaction Pairs are NOT Balanced Forces

Review PowerPoint 3 Unit EM Lesson 3 through 4

● Slowing and Stopping 1. Why do moving objects tend to slow down and then stop? **he force of friction opposes the motion of an object, causing moving objects to lose energy and begin to slow down. i. Thermal Energy **internal energy present in a system in a state of thermodynamic equilibrium by virtue of its temperature 2. Where does the energy go? ii. Law of Conservation of Energy **The law of conservation of energy states that energy can neither be created nor destroyed - only converted from one form of energy to another. This means that a system always has the same amount of energy, unless it's added from the outside. ● Friction as an Interaction (Friction (always opposes motion!) 1. What happens to the rate of change of speed of moving objects as the amount of friction changes? **friction gets involved....The force of friction opposes the motion of an object, causing moving objects to lose energy and slow down. When objects move through a fluid, such as air or water, the fluid exerts a frictional force on the moving object.

Review PowerPoint 2 Unit FM Lesson 5

● When a single force acts on an object, how is the object's motion affected by i. the strength of that force AND the object's mass ● Newton's 2nd Law (written 3 different ways) **Rate of change in speed=strength of net force/ mass (a=F/m) **Force=mass x acceleration (F=ma) **Mass=Net force/change in speed (m=F/a) i. When acceleration is constant, if the mass goes up, the force must go up also-directly proportional ii. When force is constant, if the mass goes up, the acceleration will decrease-inversely proportional iii. When mass is constant, if the force increases, the acceleration will also increase-directly proportional ■ There WILL be calculations using this (No, they will not be especially difficult. Yes, you will need to be able to know which numbers go where in the formula.) **Force is measured in Newtons (N) **Mass is measured in kilograms (kg) **Acceleration=change in speed is measured in m/s2