Mid term physics

What is the difference between a hypothesis and a theory?

"Hypotheses, theories and laws are rather like apples, oranges and kumquats: one cannot grow into another, no matter how much fertilizer and water are offered," (Alina Bradford, Live Science Contributor). A hypothesis is a limited explanation of a phenomenon; a scientific theory is an in-depth explanation of the observed phenomenon. A hypothesis is an attempt to explain phenomena. It is a proposal, a guess used to understand and/or predict something. A theory is the result of testing a hypothesis and developing an explanation that is assumed to be true about something.

What is the average velocity of a motorcycle whose initial velocity is 12.1 m/s and constantly accelerate until their final velocity 22.6 seconds later is 15.8 m/s?

(12.1 m/s + 15.8 m/s)/2 = 14.0 m/s

-We will never know how life started on Earth. -The Milky Way is a spiral-type galaxy. -Black holes exist. -The sun will rise tomorrow morning. -The Earth is older than 10,000 years. -Genetic mutations cause organisms to change over time.

-belief -fact -fact -hypothesis -fact -fact

-There are such things as ghosts. -The solar system formed from a primordial disk of gas and asteroidal material. -Matter can be converted into energy. -The positions of the planets and stars can cause humans to act in specific ways. -Momentum is the product of a body's mass and its velocity. -The core of the Sun has a temperature of 14.5 million Centigrade.

-belief -hypothesis -fact -belief -law -fact

-Primitive human-like creatures existed 2 million years ago. -If I jump out a window I will die. -The universe was created at the Big Bang. -The first generations of stars appeared about 100 million years after the Big Bang. -Space exists in 10-dimensions not just 3. -Some numbers are more lucky than other.

-fact -fact -hypothesis -hypothesis -hypothesis -belief

-There are fossils of creatures that share more physical characteristics with humans than with other primates. -Light is an electromagnetic phenomenon described by Maxwell's Law. -Matter is comprised of atoms. -The sun will die in 7.5 billion years. -Earth's magnetic field is generated by the movement of the planet's iron core. -Sunspots are colder than the surface of the Sun.

-fact -theory -fact -hypothesis -theory -fact

-For every action, there is an equal and opposite reaction. -F = m*a -Water freezes at 32 F. -The Earth is a sphere. -Gravity affects light. -Humans were created separately from all other life on Earth.

-law -law -fact -fact -fact -belief

Earth exerts a 1.0 N gravitational force on an apple. What is the magnitude of the gravitational force the apple exerts on Earth?

1.0 N

What is the average speed of a cyclist that bikes a distance of 125 km in a time of 360 min?

125 km / 360 min = 0.347 km/min (make sure you can convert this to m/s or another unit!)

The average speed of a horse that gallops a distance of 18.2 km in a time of 33.9 minutes is...

18.2 km/33.9m = 0.537km/m X 60m/1 hour = 32.2km/h

It takes 26.5 seconds for a ball to roll 3.95 meters. What is its average speed?

3.95m/26.5s = .149m/s

A 176 kg object is being pushed with 35.5 N of force on a frictionless surface. What is the acceleration?

35.5N/176kg = 0.202m/s/s

A force can be described as a ______ or a_______ and is measured in __________.

A force can be described as a push or a pull and is measured in Newtons

Define acceleration.

Change in velocity (speed or direction). The rate at which an object's velocity is changing per unit time.

Where in a lab report does this statement go: For every 2 cm of increased width of wings, airplanes flew 12 cm further.

Conclusion (could possibly in the discussion, is is better suited for the conclusion because it summarizes the data using a quantity)

Where in a lab report does this statement go: It was difficult to throw the airplane with the same force every time, but the same person was the thrower to minimize error.

Discussion

Where in a lab report does this statement go: Our data shows that paper airplanes made from stiffer paper flew significantly further.

Discussion (could possibly also be in conclusion, but is better suited for the discussion where the trend would be better explained later in the paragraph)

What is the name of the length of the straight line drawn from an object's initial position to the object's final position?

Displacement

During five seconds, a car moves 15 feet. After five more seconds, the car has moved a total of 30 feet. At 15 seconds the car has moved a total of 45 feet. This object is moving at a ____________ of _____ ft/s.

During five seconds, a car moves 15 feet. After five more seconds, the car has moved a total of 30 feet. At 15 seconds the car has moved a total of 45 feet. This object is moving at a constant velocity of 3 ft/s.

An object is being pulled with 15.2 N of force and accelerates at 3.68 m/s2. What is the mass?

F = (m)(a); (15.2) = (m)(3.68), m = 3.94 kg

What is the force of attraction from gravity of an object with a mass of 3.62 x 1016 kg and another with a mass of 5.97 x 106 kg if they are 3.84 x 102 m apart?

F = 6.67 X 10-11 X () = 9.78 X 107 N

A 45.0 kg object accelerating at 4.85 m/s2. What is the force being applied?

F = ma so F = 45.0kg X 4.85m/s2 = 218N

An object is being pulled with 6.88 N of force and accelerates at 72.9 m/s2. What is the mass?

F = ma à m = F/a à 6.88N/72.9m/s2 = 0.0944 kg or 94.4 g

A block is pushed East with a 10.2 N force and pushed West with a 5.6 N force. What is the net force on the block?

Fnet = East

Define gravity and describe how it works.

Gravity is the force of attraction of matter for other matter; it is the result of the warping or bending of the fabric space-time.

Where in a lab report does this statement go: Paper airplanes that are shorter will fly further because they have less mass.

Hypothesis

Compared with the force that brings a small car to a stop, the force required to bring a heavy truck traveling at the same speed to a stop...

If originally moving at the same velocity and if both stop in same amount of time, a more massive vehicle would require more force to stop.

What happens to the gravitational force between two masses when the distance between the masses is doubled?

If the distance is doubled, the force is cut to one-fourth.

What is the difference between a law and a theory?

In general, a scientific law is the description— often mathematical descriptions —of an observed phenomenon. It doesn't explain why the phenomenon exists or what causes it. The explanation of a phenomenon is called a scientific theory. It is a misconception that theories turn into laws with enough research.

What is the slope of a line drawn tangent to a point on the curve of a position versus time graph?

Instantaneous velocity

How do you answer the question, "What keeps a satellite up?

Its speed; it is falling all the time.

"What model of sedan (Toyota or Honda) can drive the most miles on 5 gallons of gas?" What is the independent variable in this question?

Model of sedan (Toyota or Honda)

Why does the number of trials change the accuracy of the results?

More trials tends to improve the accuracy of the data because the impact of outliers or the occasional source of errors is decreased.

Is this statement qualitative, quantitative, or neither (opinion): The teacher is a wonderful.

Neither (opinion or belief)

Kepler's three statements and Newton's equation for gravitational attraction are called "laws." Were they ever theories? Will they ever become theories? Explain.

No. A scientific law is a statement of what has been observed to happen many times. A theory explains scientific results. None of these statements offers explanations for why the motion of planets are as they are or for why gravitational attraction acts as it does.

Is the area swept out per unit of time by Earth moving around the Sun equal to the area swept out per unit of time by Mars moving around the Sun? Explain.

No. The equality of the area swept out per unit of time applies to each planet individually

"What is the biggest spider that has ever existed?" Is this question scientific? If you picked "No," re-write the question so it is scientific.

Not scientific (no way to validate if the answer is correct.) Alternative: What is the average size of an adult black widow spider in Arizona compared to Alaska.

What would happen to the value of G if Earth were twice as massive, but remained the same size? Why?

Nothing. G is a universal constant, and it is independent of Earth's mass.

What is an observation and how is it used in the scientific process?

Noticing something that happens naturally or in an experiment. Observations can lead to questions, hypotheses, or help form conclusions.

What is the relationship between observations/data and inferences/explanations in the scientific process?

Observations and data are evidence that scientists are able to make inferences based upon and create explanations for the phenomena being investigated. Explanations MUST be based on empirical data, not beliefs.

Is this statement qualitative, quantitative, or neither (opinion): The painting is ugly

Opinion

"What kind of fruit do babies like best?" Is this question scientific? If you picked "No," re-write the question so it is scientific.

Poorly worded and difficult to test. Better: "What percentage of 9 month-old babies swallow a spoonful of avocado compared to mashed banana?"

Where in a lab report does this statement go: Planes were tossed with feet side by side at the end of the measuring tape.

Procedure

Is this statement qualitative, quantitative, or neither (opinion): It requires less force to move an object with less mass.

Qualitative

Is this statement qualitative, quantitative, or neither (opinion): It requires twice the force for to lift an object using the lever.

Quantitative

Is this statement qualitative, quantitative, or neither (opinion): The metal block has a density of 2.30 g/mL.

Quantitative

Is this statement qualitative, quantitative, or neither (opinion): The sign hue is 740 nm.

Quantitative

Where in a lab report does this statement go: Planes with an 8cm wingspan flew 348cm, 467cm and 456cm.

Results

Describe what "science" is and is not able to study:

Science is the systematic study of the universe and naturally occurring phenomenon based on observations and empirical evidence. Science is not able to study supernatural phenomena that cannot be controlled for and tested.

"Which brand of dish soap makes the most bubbles?" What is the dependent variable in this question?

The amount of bubbles.

Re-write this statement using passive voice: We pulled the block using horizontal force.

The block was pulled using a horizontal force

When a car's velocity is positive and its acceleration is negative, what is happening to the car's motion?

The car is slowing down

During five seconds, a car moves 15 feet. After five more seconds, the car has moved a total of 30 feet. At 15 seconds the car has moved a total of 45 feet. If the car maintains this motion, what will happen at 20 seconds?

The car will have moved a total of 60 feet.

An elephant moves a crate. The action force is the elephant's trunk pushing on the crate. What is the reaction force?

The crate pushing on the elephant's trunk.

Explain how a dog that has moved can have a displacement of zero.

The dogs initial position and final position are the same

You see a skateboard rolling across a sidewalk. As you watch, the skateboard slows down and eventually stops. Why?

The force of friction acts in the opposite direction of the motion of the object, causing negative acceleration.

If an object in motion tends to stay in motion, why does a soccer ball stop rolling?

The force of friction is acting on the ball, so the ball is not in equilibrium.

The force of gravity depends on objects' _______ and ________.

The force of gravity depends on objects' masses and distance from each other.

The Moon and Earth are attracted to each other by gravitational force. Does the more-massive Earth attract the Moon with a greater force than the Moon attracts Earth?

The force the Earth exerts on the Moon is exactly the same as the force the Moon exerts on the Earth (but they act in opposite directions).

You accelerate two identical objects. You accelerate the second object more than the first. How does the force used compare?

The force used to accelerate the second object is greater.

A girl catches a Frisbee. Consider the action force to be the impact of the Frisbee against the girl's hand. The reaction to this force is the...

The girls hand pushes against the Frisbee.

Distinguish between the displacement of a traveler who takes a train from New York to Boston and the displacement of a traveler who flies from Boston to New York. Be sure to compare the magnitudes of the displacements.

The magnitudes of the displacements are equal, but the displacements are in opposite directions. Therefore, one displacement is positive and one displacement is negative.

Re-write each statement using passive voice: I pulled the mass and read the force measured on the spring scale.

The mass was pulled and the force was measured using a spring scale.

How does the number of trials affect an experiment?

The more trials you have the more reliable your data will be. Errors in data will have a smaller effect because when you average more trials it will be closer to the actual value (i.e. if 1 trial out of 3 has a large error, it will have a large effect on the average as opposed to 1 trial out of 15).

Two objects are pushed with the same force. One object has a mass of 1.0 kg and the other object has a mass of 2.0 kg. What will happen?

The object with less mass will have a greater acceleration.

Re-write each statement using passive voice: Attach the pendulum with a length of 22 cm to the support bar.

The pendulum with a length of 22 cm was attached to the support bar.

Define velocity

The rate of change in position (speed with a direction).

What does it mean for an object to be in free fall? A free falling object is an object that is falling under the sole influence of gravity.

There are two important motion characteristics that are true of free-falling objects: - Free-falling objects do not encounter air resistance. - All free-falling objects (on Earth) accelerate downwards at a rate of 9.8 m/s/s

Earth exerts a 1.0 N gravitational force on an apple. Does the apple accelerate toward Earth, or does Earth accelerate toward the apple? Explain your answer.

They both accelerate toward each other. Earth's acceleration is extremely small compared to that of the apple because Earth has a much greater mass than the apple does.

"How does the size of the maze affect the time it takes to complete the maze?" The dependent variable is...

Time to complete the maze

A mountain bike rider enters a jump travelling at 6.7 m/s. The rider lands the bike going 5.65 m/s. The jump took 0.731 seconds. What is the rider's average velocity during the jump? What is the rider's acceleration during the jump?

Vav = = 6.2 m/s a = = -1.4 m/s2

An object moves at a steady 8.0 m/s East. This object has constant...

Velocity, speed, acceleration

Mass is the amount of matter contained in a body. Mass of the body is the constant quantity. It does not change with the change of position or location.

Weight is the force exerted on an object. It depends upon the gravitational field Weight of the object is the variable quantity and changes with the change in position and location due to the acceleration of the gravitational force acting on it.

Ms. Sophiea was told about a new shampoo that makes color last longer. She dyes her hair green and uses her regular shampoo on half her head, but the new shampoo on the other half of her head for a week. Although balding, she also convinces her husband to dye his hair green and do the same treatments for a week. At the end of the week, the brightness of the green hair on each side of the head is compared. -What is the independent variable in the experiment above? -What is the dependent variable in the experiment above? -How many trials were in the experiment above? -What could be done to make this experiment better and WHY would this improve the experiment?

What is the independent variable in the experiment above? Type of shampoo What is the dependent variable in the experiment above? Brightness of green hair color How many trials were in the experiment above? 1 (the single trial for Ms. Sophiea compared to the single trial for Mr. Garbe) What could be done to make this experiment better and WHY would this improve the experiment? More trials, same type of hair (original color, quantity, length)

Define terminal velocity.

When the upward force from air resistance is balanced by the downward force from gravity, the object is in equilibrium and is moving at a constant velocity.

A toy car is rolled down a 2.0 meter ramp onto a horizontal surface. The car is travelling 5.19 m/s when it enters the horizontal surface and travels at a negative acceleration (due to friction) of 0.50 m/s2. What is the final position after 3.00 seconds?

X = ½ (-0.50m/s2)(3.00s)2 + 5.19 m/s X 3.00 s = -2.25m + 15.57m + 2.0m = 15.3m

A marble is released from 137.6 m and takes 5.3 seconds to hit the ground. What is the marble's acceleration?

X = ½ at^2 137.6 m = ½ a(5.2s)^2 137.6 m = 13.52s2 a a = 9.81 m/s^2

Does scientific knowledge change? If so, how

Yes, new evidence and data is collected/discovered and scientific ideas are adapted/discarded/developed to be consistent with the evidence.

"How quickly does an agutí run through a maze compared to a rat?" Is this question scientific? If you picked "No," re-write the question so it is scientific.

Yes.

The initial velocity of a car is 7.2 m/s and the final velocity is 0.0 m/s. What is the acceleration if the car takes 6.2 seconds to come to a stop?

a = (V - U) / t = (0.0 - 7.2) / (6.2) = -1.2 m/s^2

What is the acceleration of a 7.56 kg object when a force of 84.5 N is applied?

a = F/m 84.5N/7.56kg = 11.2m/s2

A 3.79 kg object is being pushed with 12.1 N of force. What is the acceleration?

a = F/m = 12.1N/3.79kg = 3.19m/s2

Where in a lab report does this statement go: What is the effect of the type of paper on the time a paper airplane stays in the air?

background (or Question/Variables)

"How many miles can different brands of tires be driven without getting a flat?" The independent variable in this question is...

brands of tires

When is an object in equilibrium? What is required to cause an object to accelerate?

An object is in equilibrium when all forces acting on an object or balanced (the net force is 0). An unbalanced (net) force greater than 0 causes an object to accelerate.

What is the relationship between equilibrium and the net force?

An object is in equilibrium when the net force is 0.

What is inertia?

An object's resistance to a change in motion (speed and/or direction).

Earth moves more slowly in its orbit during summer in the northern hemisphere than it does during winter. Is it closer to the Sun in summer or in winter? Explain.

Because Earth moves more slowly in its orbit during summer, by Kepler's second law, it must be farther from the Sun. Therefore, Earth is closer to the Sun in the winter months.

In the airplane experiment, the dependent variable is the...

distance the airplane flew.

The moon has a mass of Moon 7.348x1022 kg and a satellite has a mass of 2015 kg. The distance between them is 3.84x105 m. What is the force of attraction from gravity?

g = 6.67 X 10-11 X (7.348 X 1022 kg X 2015 kg)/(3.84 X 105 m)2 = 6.70 X 104 N

When dropped from the same height, a bowling ball hurts more than a ping pong ball dropped on your foot because the bowling ball hits your foot with more force. The bowling ball hits with more force primarily because...

it has a larger mass.

An independent variable is the part of an experiment that you...

manipulate in order to test the effect of it.

In the bungee egg experiment, the independent variable was the...

mass of the object dropped and also the number of rubber bands that made the bungee cord

You accelerate two objects equally. All other things being equal, the object with more matter (mass) requires

more force.

As a ball falls, the action force is the pull of the Earth's mass on the ball. The reaction force is the...

pull of the ball's mass on the Earth.

Is this statement qualitative, quantitative, or neither (opinion): The box is made of plastic.

qualitative

Is this statement qualitative, quantitative, or neither (opinion): The car is blue.

qualitative

How much time would it take a rock to fall from 12.45 meters to the ground? Assume the rock is dropped (vi = 0 m/s) and air resistance is not a factor.

x = ½(g)(t^2); 12.45 = ½(9.81)(t^2); t = 2.54 s

"What type of fertilizer increases plant growth the most?" Is this question scientific? If you picked "No," re-write the question so it is scientific.

yes

What is the speed of an object at rest?

zero