Physics Final

A 1-N balloon is suspended in air, drifting neither up nor down. (a) How much buoyant force acts on it? (b) What happens if the buoyant force decreases? (c) What happens if it increases?

(a) 1 N up; (b) it falls; (c) it rises.

Rank from greatest to least the volume of water at these temperatures:

10 ∘C, 0 ∘C, 4 ∘C

Calculate the pressure on your finger when you balance a 2-kg ball on the tip of your finger, which has an area of 1 cm2.

196200 Pa Pressure= F/A Force= mg----> 2kg * 9.81 m/s2= 19.62 N (19.62 N/cm2)*(100 cm/1 m)^2= 196200 Pa

A 3-m-tall barrel is filled with water (with a weight density of 10,000 N/m3). Calculate the water pressure on the bottom of the barrel.

30 kPa 10,000* 3

When a 1-m-tall barrel is filled with water, the pressure at the bottom of the barrel is 10 kPa. If you close the top and extend a thin empty 3.2-m tall pipe on top, the pressure at the bottom of the barrel is still 10 kPa. If you then fill the pipe with water, the effective height of the water from the bottom of the barrel is 4.2 m. What is the pressure at the bottom of the barrel when water is added to fill the pipe to its top? (This activity sometimes bursts a barrel!)

42 kPa 4.2*10= 42 kPa

If the pressure in a hydraulic press is increased by an additional 10 N/cm2, how much extra load will the output piston support if its cross-sectional area is 50 cm2?

500 N

Calculate the water pressure at the bottom of a 70-m-high water tower.

784800 Pa (1000)*(9.81)*(70)= 784800 Pa

Distinguish between a calorie and a Calorie. Between a calorie and a joule.

A Calorie is 1000 calories. A calorie is 4.19 joules.

Estimate the buoyant force that air exerts on you. (To estimate your volume assume your density is about that of water.) Assume that your weight is a about 800 N, for example.

F= 1.0 N mass= 800/9.81= 81.549 volume= 81.549/1000= .08154 1.2* .081= .0972 .0972*9.81= .953 N

An airplane has a total wing surface of 80 square meters. At a certain speed the difference in air pressure below and above the wings is 4% of atmospheric pressure. Calculate the lift on the airplane.

F= 320000 N .04*80= 3.2 3.2*10^5= 320,000

Each of the following items states a temperature, but does not tell you whether the temperature is measured on the Fahrenheit, Celsius, or Kelvin scale. Match the items to the appropriate temperature scale.

Fahrenheit scale (°F) A hot summer day might be 100. Ice cream is stored in freezers at 26. Celsius scale (°C) Water freezes into ice at 0. A typical room temperature is 24. Liquid water boils at 100. Kelvin scale (K) The coldest possible temperature is 0. Water boils into gas phase at 373.15.

Select the correct equations that show how the food value in calories per gram is 5.7 kcal/g (or 5.7 Cal/g ).

Food value per gram=(Food value)/mpeanut=(3.42Cal)/(0.6g)=5.7Cal/g

Assuming that 40% of the heat released by the burning peanut makes its way to the water (40% efficiency), select the correct equations that show that the peanut's food value is 3420 calories (equivalently, 3.42 Calories).

Food value=(cmwaterΔT)/0.40=(1.0cal/(g⋅∘C))(57g)(46∘C−22∘C)/0.40=3420cal

In which direction does internal energy naturally flow between hot and cold objects?

From high temperature to low temperature

Select the correct equations that show that 8380 joules are required to raise the temperature of the mass 0.20 kg of water from 22∘C to 32∘C. For the specific heat capacity c, use 4190 J/kg⋅∘C

Q=cmΔt=(4190J/kg⋅∘C)(0.20kg)(32∘C−22∘C)=8380J

The specific heat capacity of ice is about 0.5 cal/g⋅∘C. Assuming that it remains at that value all the way to absolute zero, calculate the number of calories to change a 1.2-g ice cube at absolute zero (-273∘C) to 1.2 g of boiling water. How does this number of calories compare with the number of calories required to change the same 1.2 g of 100∘C boiling water to 100∘C steam?

Qi−w = 379.8 cal a) temp. change from -273 C to melting 0 C: cm△T= (.5 cal/g)*(1.2 g)*(273)= 163.8 cal b)phase change from ice to liquid: mL= (1.2 g)*(80 cal/g)= 96 cal c)temp. change from 0 C to 100 C for boiling: cm△T= (1 cal/g)*(1.2 g)*(100)= 120 cal d)Energy used: 163.8 + 96 + 120= 379.8 cal Qi−w/Qw−s= .59 a) temp change: cm△T= (1)*(1.2)*(0)= 0 b) phase change: mL= (1.2)*(540 cal/g)= 648 c) 379.8/648= .59

Relatively speaking, do high-frequency waves have long wavelengths or short wavelengths? Name an electromagnetic wave with higher frequency than blue light.

Short, ultraviolet

According to the law of conservation of energy, if ocean water cools, something else should warm. What is it that warms?

The cooling ocean warms the air.

What does a windchill of -20°C mean?

The cooling rate will be the same as if the temperature were -20°C without wind.

The large piston of a hydraulic lift has an area twice the area of the small piston. In comparison to a force applied on the small piston, what would the force exerted by the large piston be?

The large piston would have double the force.

What happens to the speed of a molecule when it hits an oncoming faster molecule? When it hits a receding one?

The speed increases in the former case and decreases in the latter case.

The specific heat capacity of steel is 450 J/kg⋅∘CJ/kg⋅∘C. How does this compare with the heat needed to raise the temperature of the same mass of water through the same temperature difference?

This value is less than the heat needed to raise the temperature of the same mass of water through the same temperature difference.

Which of the following changes would make the water balloon more likely to pop? (Ignore effects of convection within the fluid.)

Use a thicker balloon. Use a liquid that has a lower heat capacity than water.

Your friend of mass 100 kg can just barely float in freshwater. Calculate her approximate volume.

V= 0.10 m3 V=m/d 1000/10= .1

A 88-kg mountain-climber friend ponders the idea of attaching a helium-filled balloon to himself to effectively reduce his weight by 25% when he climbs. He wonders what the approximate size a balloon would be. Share with him your calculations that find the volume of the balloon.

V= 18 m3 density of air= 1.2 kg/m3 to lift .25* 88 kg= 22 kg 22/1.2= 18 m3

On a perfect fall day, you are hovering at rest at low altitude in a hot-air balloon. The total weight of the balloon, including its load and the hot air in it, is 18000 N. a. Find the weight of the displaced air. b. Find the volume of the displaced air.

W= 18000 N V= 1500 m3 density of air= 1.2 kg/m3 density*g*V=18000 1.2*9.81= 11.772 18000/11.772= 1529 m3

Which of these has the highest specific heat capacity?

Water

Why does evaporation cool the liquid left behind?

When the fastest molecules leave during evaporation, the slower, cooler ones remain.

Consider the set of tubes shown in the figure. Each tube contains an unknown fluid that is less dense than the water it floats on top of. Rank the four unknown fluids from least dense to most dense.

a c, b, d

a) What is the period, in seconds, that corresponds to the frequency of 10 Hz? b) What is the period, in seconds, that corresponds to the frequency of 0.2 Hz? c) What is the period, in seconds, that corresponds to the frequency of 70 Hz?

a) T= .10 s Use T= 1/f-------> T= 1/10= .10 s b) T= 5 s c) T= .014 s

Consider 58 g of hot water at 88 ∘C poured into a cavity in a very large block of ice at 0∘C. a) What will be the final temperature of the water in the cavity? b)Find what mass of ice must melt in order to cool the hot water down to this temperature.

a) T= 0 C b) m= 63.8 g Temp change: cm△T= (1)*(58)*(88)= 5104 cal phase change: Q=mL---> m=Q/L 5104=Q/80-----> 5104/80= 63.8 g

a) Place the single weight with a known mass on the spring and release it. Eventually, the weight will come to rest at an equilibrium position, with the spring somewhat stretched compared to its original (unweighted) length. At this point, the upward force of the spring balances the force of gravity on the weight. With the weight in its equilibrium position, how does the amount the spring is stretched depend on the value of the weight's mass? b) Use the simulation to compare the masses of the three colored and unlabeled weights of different sizes. To do so, set the spring constant of both springs to the same value. Hang known weights on the left spring and an unknown weight on the right spring, and compare the two. Use as many known weights as necessary to determine the unknown masses, and then place each into the appropriate mass bins in the ranking task below. Do the same for all three unknown weights. c)Recall that in the equilibrium position, the upward force of the spring balances the force of gravity on the weight. Use this concept, along with the variable mass value, the ruler, and the moveable line, to estimate the spring constant k of the spring. Set the damping to "Lots" so that the mass will come to rest quickly after being changed, and make sure the gravity is set to "Earth." Finally, set the spring constant to "Small." Estimate the spring constant several times (using different values of mass) and average together for the most accurate calculation. d) When is the elastic potential energy of the spring a maximum? e) When is the kinetic energy of the mass a maximum? f) Select Earth in the menu box so that there is now a force of gravity. Now the total energy of the weight/spring/Earth system is the sum of the kinetic energy, the elastic potential energy, and the gravitational potential energy. When is the kinetic energy a maximum? (It may help to watch the simulation in slow motion). g) How does the frequency of oscillation depend on the value of the mass? h) The amplitude of oscillation is the maximum distance between the oscillating weight and the equilibrium position. Determine the frequency of oscillation for several different amplitudes by pulling the weight down different amounts while still keeping the simulation within the top and botom boundaries. How does the frequency depend on the amplitude of oscillation? i) The spring constant can be adjusted with Spring Constant slider bar ("larger" means a greater spring constant, or stiffer spring). How does the frequency of oscillation depend on the spring constant?

a) The spring stretches more for a larger mass. b) magenta small sized weight: 50 g < M < 100 g blue medium sized weight: 100 g < M < 250 g gold large size weight: 100 g < M < 250 g c) k = 3.0 N/m d)Both when the spring is most compressed and when the spring is most stretched e) When the spring is at its unweighted length (when it isn't stretched or compressed) f) When the mass is at the equilibrium position g) The frequency decreases as the mass increases. h) The frequency is independent of the amplitude. i) The frequency increases as the spring constant increases.

a) What is the frequency, in hertz, that corresponds to the period of 0.10 s? b) What is the frequency, in hertz, that corresponds to the period of 5 s? c) What is the frequency, in hertz, that corresponds to the period of 1/20 s?

a) f= 10 Hz f=1/T----> 1/.10=10 b) f= .2 Hz c) f= 20 Hz f=1/T 1/20 s= .05 s 1/.05= 20

a) What do you use a pressure cooker for? b) How does using a pressure cooker affect the amount of internal energy in the water inside the pressure cooker, and why? c) How does the pressure exerted by bubbles in the water compare with the atmospheric pressure when the temperature of water in an open pressure cooker is below 100 d)What happens to water at room temperature if you decrease the atmospheric pressure around it?

a) to prevent boiling and cooling b) It increases the amount of internal energy because it does not allow the heat to boil the water. c) The pressure exerted by the bubbles is less than the atmospheric pressure below 100∘C and equals the atmospheric pressure at 100∘C d) It will first boil and then freeze.

What happens when you heat ice that is at -40∘C? What happens when you heat ice that is at 0∘C? What happens when you heat water that is at 0∘C? What happens when you heat water that is at 100∘C?

a)The temperature increases until the ice reaches its melting point. b)The temperature stays constant until all the ice is melted. c)The temperature increases until it reaches 100∘C. d)The temperature stays constant until all the water is boiled.

In lab you find that a 1-kg rock suspended above water weighs 10 N. When the rock is suspended beneath the surface of the water, the scale reads 8 N a. What is the buoyant force on the rock? b. If the container of water weighs 10 NN on the weighing scale, what is the scale reading when the rock is suspended beneath the surface of the water? c. What is the scale reading when the rock is released and rests at the bottom of the container?

a. 2 N b. 12 N c. 20 N

Rank the buoyant force supplied by the atmosphere on the following, from most to least:

an elephant a skydiver at terminal velocity a helium-filled party balloon

A thermos bottle controls heat transfer by limiting _________.

conduction, convection, and radiation

Newton's law of cooling applies to objects that undergo _________.

cooling or warming

Hot sand cools off faster at night than plants and vegetation. This indicates that the specific heat capacity for sand is ___________.

less than that of plants

Suppose that we replace the aluminum with a mystery metal and repeat the experiment in the video. As in the video, the mass of the metal is the same as that of the water. Room temperature is about 20 ∘C before the start of the experiment. The water heats up to 40 ∘C, and the mystery metal heats up to 80 ∘C. Compared to that of water, the heat capacity of our mystery metal is

one-third as great.

A skipper on a boat notices wave crests passing his anchor chain every 4.2 s. He estimates the distance between wave crests to be 17 m. He also correctly estimates the speed of the waves. Find this speed.

v= 4.0 m/s Find the frequency: f= 1/T-----> 1/4.2= .23809 Hz v=λ*f 17*.23809= 4.0 m/s

How fast does a 200-Hz sound wave with a wavelength of 3.1 m travel?

v= 620 m/s v= λ*f λ= lambda (wavelength): 3.1 m f= frequency: 200 Hz 3.1*200= 620 m/s

Radioactive decay of granite and other rocks in Earth's interior provides sufficient energy to keep the interior molten, to heat lava, and to provide warmth to natural hot springs. This is due to the average release of about 0.030 J per kilogram each year. Find an increase in temperature for a thermally insulated chunk of granite that takes about 12.5 million years to change temperature. (Assume that the specific heat capacity c of granite is 800 J/kg⋅C. Use the equation Q=cmΔT.)

△T= 468.75 C∘ Heat released in 1 year= .030 J in 12 years that would be (.030)*(12,500,000)=350,000 m= 1 kg c= 800 J/kgC Change in temperature= △T= Tf-Ti 350,000 J/kg= (1 kg)* (800 J/kgC)* (△T) △T= 468.75 C∘

Rank the bottom pressures from most to least for the following:

10-cm-tall container of mercury. 20-cm-tall container of saltwater. 20-cm-tall container of freshwater.

A biker increased his velocity from 2 m/s to 8 m/s in 3 seconds moving in a straight line. What is the acceleration of the biker?

2 m/s2 a= △v/△t △v= 8-2= 6 6/3= 2

A medium size apple weighs 1 N and sits on an area of about 4 cm2 (0.0004 m2). Determine the pressure that the apple exerts on the surface.

2,500 Pa

A dike in Holland springs a leak through a hole of area 0.80 cm2 at a depth of 2.8 m below the water surface. How much force must a boy apply to the hole with his thumb to stop the leak, and in effect, hold back the whole ocean? Could he do it?

2.2 N .80*2.8= 2.2 yes

How much support force acts on a 200-N girl standing on a weighing scale?

200 N

A space probe of mass 1,000 kg is launched to Jupiter. How much would it weigh once at Jupiter? (Assume Jupiter's gravitational acceleration to be 24.79 m/s².)

24,790 N

The depth of water behind the Hoover Dam is about 250 m. Calculate the water pressure at the base of this dam.

2452500 Pa 1000*9.81*250= 2452500

Which one of these values is the lowest temperature?

270 K

While you are sitting in a park, you notice a bus moving at 3 m/s to your right and a passenger that starts walking to the back of the bus but who seems to stay at the same position in front of you. What is the velocity of the passenger respect to the bus driver?

3 m/s to your left

Three water samples of different masses are warmed from room temperature to 50∘C using identical burners and then removed from the burners and allowed to cool. Rank the water samples according to the heat released from each as they cool back down to room temperature. Water has a specific heat of 4190⋅J/kg⋅ ∘C.

3.8 kg of water, 1.2 kg of water, 1.0 kg of water

The large positive charge inside the shell causes equal in magnitude charges distributed on the inner and outer surfaces of the spherical shell. Which of the pictures best represents the charge distribution on the inner and outer walls of the shell? (Figure 1)

4

What beat frequency will occur when a 370-Hz and a 374-Hz sound source are sounded together?

4 Hz

How many joules (J) are needed to change the temperature of 1 gram of water by 1°C?

4.19 J

Rank the scale readings from most to least. (Ignore friction.)

A, B C (in the middle)

Why does energy added to boiling water not increase the temperature of the water?

Boiling is a cooling process, so energy is removed as quickly as it is added.

What is the value of the velocity of the ball when it reaches its maximum height? What is the acceleration of the ball when it is moving up, when it is at the maximum height, and when it is moving down? (Note: The acceleration graph is shown in red.)

It is always zero. It is always negative.

Rank the speed of sound through the following from greatest to least:(a) Helium(b) Benzene(c) Mercury

Mercury, Benzene, Helium

Select the correct equations that show that 60 W of power is required to impart 180 J of energy to something in 3 s.

P=W/t=(180J)/(3s)=60W

If you push on a crate with a horizontal force of 120 N and it slides at constant velocity, how much is the friction acting on the crate?

The frictional force on the crate is 120 N opposite the direction of motion.

What is the resultant of a 40-N horizontal force and a 30-N vertical force?

The resultant is a force with a magnitude of 50.00 N.

When building bridges, there are gaps left between the different plates. What is the reason for this?

To leave room for heat-related expansion.

When you stand at rest on a bathroom scale, how does your weight compare with the support force from the scale?

Your weight is equal in magnitude and opposite in direction to the support force from the scale.

Rank, from smallest to largest, the pressures in the tank of motionless fluid shown in the figure.

a, b c d, e, f

If while riding in a smooth-riding train, you toss a coin upward, the coin will normally land ______.

in your hand

A car moving in a circular track at 45 km/h is moving with constant ______________.

speed

The large positive charge inside the shell causes equal in magnitude charges distributed on the inner and outer surfaces of the spherical shell. Which of the following figures best represents the charge distribution on the inner and outer walls of the shell? (Figure 1)

1

The amount of heat needed to raise the temperature of 1 gram of water by 1°C is ___________.

1 calorie

How many calories are needed to change the temperature of 1 g of water by 1°C? To melt 1 g of ice at 0°C? To vaporize 1 g of boiling water at 100°C?

1 calorie, 80 calories, 540 calories

What is the mass of a cubic meter of air at room temperature (20°C)?

1.21 kg

If the frequency of a particular wave is 20 Hz, its period is _________.

1/20 second

Two conducting spheres are each given a charge Q. The radius of the larger sphere is three times greater than that of the smaller sphere. If the electric field just outside of the smaller sphere is E0, then the electric field just outside of the larger sphere is

1/9 Eo

What is the weight in newtons of a 1-kilogram brick resting on a table?

10 N

What is the acceleration of a car moving along a straight road that increases its speed from 0 to 100 km/h in 10 s?

10 km/h·s acceleration= △v/time velocity= displacement/time displace.= 100-0= 100 time= 10 sec 100/10= 10

A 1 kg balloon at equilibrium in the air is buoyed up with a force of __________.

10 newtons

While you are in a bus that moves at 100 km/h, you walk from the back to the front at 10 km/h. What is your speed relative to the road outside?

110 km/h.

A 12-N book is at rest on a flat table. How many newtons of support force does the table provide? What is the net force on the book?

12 newtons up 0 newtons

A positive charge is brought close to a fixed neutral conductor that has a cavity. The cavity is neutral; that is, there is no net charge inside the cavity. Which of the figures best represents the charge distribution on the inner and outer walls of the conductor? (Figure 1)

3

A ball freely falling at 20 m/s will in the next second have a speed of ______.

30 m/s

The electric potential (voltage) at a specific location is equal to the potential energy per unit charge a charged object would have if it were at that location. If the zero point of the voltage is at infinity, the numerical value of the voltage is equal to the numerical value of work done to bring in a unit charge from infinity to that location. Select Values and Grid in the menu, and drag one positive charge to the middle of the screen, right on top of two intersecting bold grid lines. Using the voltage meter, you should find that 1 m away from the charge, the voltage is 9 V. What is the voltage 2 m away from the charge? What is the voltage 3 mm away from the charge? Place several E-Field Sensors at a few points on different equipotential lines, and look at the relationship between the electric field and the equipotential lines. Which statement is true? Equipotential lines are usually shown in a manner similar to topographical contour lines, in which the difference in the value of consecutive lines is constant. Clear the equipotential lines using the Erase button on the voltage tool. Place the first equipotential line 1 m away from the charge. It should have a value of roughly 9 V. Now, produce several additional equipotential lines, increasing and decreasing by an interval of 3 V (e.g., one with 12 V, one with 15 V, and one with 6 V). Don't worry about getting these exact values. You can be off by a few tenths of a volt. Which statement best describes the distribution of the equipotential lines? Now, remove the positive charge by dragging it back to the basket, and drag one negative charge toward the middle of the screen. Determine how the voltage is different from that of the positive charge. How does the voltage differ from that of the positive charge? What is the voltage at the midpoint of the two charges? The voltage at the midpoint of the dipole is Try to have the equipotential lines equally spaced in voltage. Then, use an E-Field Sensor to measure the electric field at a few points while looking at the relationship between the electric field and the equipotential lines. Which of the following statements is true?

4.5 V 3 V At any point, the electric field is perpendicular to the equipotential line at that point, and it is directed toward lines of lower voltages. The equipotential lines are closer together in regions where the electric field is stronger. The voltages become negative instead of positive and keep the same magnitudes. Exactly twice the voltage produced by only one of the charges at the same point zero The electric field strength is greatest where the equipotential lines are very close to each other.

Water is denser at ___________.

4°C

While fishing on the pier you observe that wave crests are spaced 2 meters and are moving at about 10 m/s, what is the frequency of this wave?

5 Hz

If an input of 100 J in a pulley system increases the potential energy of a load by 60 J, what is the efficiency of the system?

60%

Consider the power dissipated by the two circuits in the video. The ratio of power dissipation in the parallel circuit to that in the series circuit is

9

Let's start with a simple circuit that you will have seen in the Ohm's Law and Power PhET tutorial, if you completed that one. What is the voltage reading across the resistor, as shown in the figure below? You should see the blue electrons flowing through the circuit, whereas (conventional) current is the flow of positive charge. You can select which current to display in the panel in the upper-right corner. Place the crosshairs of the noncontact ammeter just before each resistor to measure the current through the top and bottom resistors. How do these currents compare? The current through each resistor in the two-resistor circuit is _________ the current through the resistor in the one-resistor circuit (the circuit in Part A). The voltage across each resistor in the two-resistor circuit is ___________ the voltage across the resistor in the one-resistor circuit. For the series circuit in the previous part, change the resistance of the bottom resistor to 20 Ω. What is the voltage across this 20-Ω resistor? What must be the resistance of a single resistor connected to a 9-V battery for the current coming out of the battery to be the same as that of the circuit in Part D? Change the value of the battery emf to 10.0 V, and make sure the middle resistor is set to 20 Ω. Use extra wire for each "leg" of the circuit so you can measure the current through all legs with the ammeter. How does the current coming out of the battery change when the switch is closed? With the switch closed, how does the voltage across the 20-Ω resistor compare to the voltage across the 10-Ω resistor? For the parallel circuit in the previous part (with the switch closed), the current through the 20-Ω resistor is _________ the current through 10-Ω resistor. For the circuit in the previous part, what happens to the current flowing through the resistor on the right when the switch is closed (allowing current to flow through the resistor on the left)? With the switch open, roughly what must be the resistance of the resistor on the right for the current out of the battery to be the same as when the switch is closed (and the resistances of the two resistors are 20 Ω and 10 Ω)? The brightness of a light bulb having a specific resistance increases if the current through it increases. For the circuit shown in the figure below, how does the brightness of the light bulb change when the resistance of the 10-Ω resistor is decreased? The figures below show four circuits, with the resistances of the resistors given. In all cases, the emf of the battery is 10 V. Rank the circuits in order of descending total current coming out of the battery. (You should be able to answer this question using what you have already learned, but if you want, feel free to build the four circuits and make measurements.)

9.0 V The currents are the same. half / half 6.0 V 30 Ω The current increases. The voltage across the 20-Ω resistor is equal to the voltage across the 10-Ω resistor. less than The current flowing through the resistor on the right does not change. 7 Ω The brightness does not change. Greatest Current: 3 squared -2 squared -2 battery square Smallest Current: 3 battery square

An electric toy draws 0.80 A from a 120-V outlet. Determine how much power the toy consumes.

96 W (120)(.80)= 96

Once the crate slides, how hard a push is needed to keep it sliding at constant velocity?

A push with a force equal to and opposite the sliding friction force.

All equal-mass boxes are pulled by the same force F along a friction-free surface. Rank the following from greatest to least: (Figure 1) Rank the accelerations of the boxes. Rank the tensions in the ropes connected to the single boxes to the right in B and in C.

A, B, C B, C

In what form does radiant energy travel?

As electromagnetic waves

The siren of a fire engine is heard when the fire engine is traveling(a) toward the listener at 30 km/h.(b) toward the listener at 50 km/h.(c) away from the listener at 20 km/h. Rank the pitch heard in situations a, b, and c from greatest to least.

B, A, C

Why do we frequently see the lightning and later hear the thunder?

Because light travels faster than sound

Which of the motion diagrams in the figure below best matches the motion of the bungee jumper shown in the video? During free-fall, the acceleration of a bungee jumper ____________. Suppose a car's velocity is to the left, and its acceleration is to the right. Which of the following describes this car's motion? Four cars undergo acceleration as described by the data in the following table.

C is a nonzero constant The car is slowing down. Car B, Car A, Car D, Car C

Rank how much they resist being set into motion, from greatest to least. Rank the support (normal) force the table exerts on them, from greatest to least.

C (10 kg water), A (5 kg sand), D (1 kg pillow), B (0.5 kg iron) Nc, Na, Nd, Nb

Three parachutists, A, B, and C, each have reached terminal velocity at the same distance above the ground below (Figure 1). Rank the amount of their terminal velocities from fastest to slowest. Rank the landing time from longest to shortest.

C (75 kg), A (50 kg), B (40 kg) B, A, C

The weights of Burl, Paul, and the scaffold produce tensions in the supporting ropes. Rank the tension in the left rope, from most to least, in the three situations, A, B, and C.

C, B, A (C is when guys are closet, B is when guys are a little further, A is when the guys are farthest apart)

When the temperature of ice-cold water is increased slightly, does it undergo a net expansion or a net contraction?

Contraction

When a pot of water is being heated in a cookstove, what process takes the heat from the bottom of the pot to the surface of the water?

Convection

What is the relationship between current, resistance, and voltage difference? How does the current change if you increase the resistance, keeping the voltage difference the same? What factors does the resistance offered by a piece of conductor depend upon? How does the resistance of a thick piece of copper wire compare to the resistance of a thin piece of copper wire? What is the current in a bulb if the resistance of its filament is 2 ohms and it is connected across a 6-volt battery?

Current = Voltage Difference / Resistance The current decreases. both the geometry and the material of the conductor The resistance of the thin piece is greater than that of the thick piece. 3 amps

Rank the boiling-water temperatures from highest to lowest in these locations.

Death valley, sea level, Denver CO

When skydiver Nellie opens her parachute, the air drag pushing the chute upward is stronger than Earth's force of gravity pulling her downward. A friend says this means she should start moving upward. Why this isn't so, and what does happen?

During a short time the air resistance acting on Nellie indeed exceeds the force of gravity and produces a momentary upward net force and upward acceleration. This acceleration decreases her downward velocity but does not change its direction. The change of the speed decreases the air resistance until it is equal to the force of gravity which stops the further change of the speed.

The potential difference between a particular storm cloud and the ground is 100 million V. If a charge of 2.2 C flashes in a bolt from cloud to Earth, what is the change of potential energy of the charge?

E= 220,000,000 J V= PE/Q PE= V*Q 100,000,000 V* 2.2 C= 220,000,000 J

A droplet of ink in an industrial ink-jet printer carries a charge of 1.2×10−10C and is deflected onto paper by a force of 2.8×10−4N. Find the strength of the electric field to produce this force.

E= 2333333.333 N/C. (or 2.3 x10^6) E= F/q 2.8x10^-4 / 1.2x10^-10= 2333333.333

A car is increasing its velocity due east for 10 seconds, then slows down for 2 seconds. What is the direction of the acceleration vector for each of these events?

East then west

Distinguish between evaporation and boiling.

Evaporation happens at a liquid surface, whereas boiling occurs in the bulk of the liquid.

In the hydraulic pistons shown in (Figure 1), the small piston has a diameter of 2 cm. The large piston has a diameter of 6 cm. How much more force can the larger piston exert compared with the force applied to the smaller piston?

F1/F2= 9 2^2= 4 6^2= 36 36/4= 9

Nellie Newton applies a force of 50 N to the end of a lever, which is moved a certain distance. If the other end of the lever moves one-third as far, find the force it can exert.

F= 150 N 1/3= .3333 50/.3333= 150

If you stand next to a wall on a frictionless skateboard and push the wall with a force of 35 N, how hard does the wall push on you? If your mass is 75 kg, find your acceleration.

F= 35 N a= .47 m/s2

Knowing that k is 9.0×109N⋅m2/C2 (the proportionality constant for Coulomb's law), select the correct equations that show that the force between the charges is 9.0×109N.

F= kq1q2/r2

Two point charges, each with 0.4 C of charge, are 0.5 m apart. Given that k=9.0×109N⋅m2/C2 (the proportionality constant for Coulomb's law), select the correct equations that show that the force between the charges is 5.76×109N.

F= kq1q2/r2 = (9.0x10^9 Nm2/C2)(0.4 C)(0.4 C)/ (0.5 m)2

Calculate the net force produced by a 60-N force and a 20-N force if both forces act in the same direction. Calculate the net force produced by a 60-N force and a 20-N force if both forces act in opposite directions.

Fa = 80 N Fb = 40 N

Does sound travel faster in warm air or in cold air? In humid air or dry air?

Faster in warm air, faster in humid air

Atomic physicists ignore the effect of gravity within an atom. To see why, calculate and compare the gravitational and electrical forces between an electron and a proton separated by 10−10m. The charges and masses are given in the textbook.

Felec/Fgrav= 2 x 10^39 Fe= kq1q2/r2= (9x10^9)(1.6x10^-19)(1.6x10^-19)/(10^-10)^2= 23.04x10^-9 Fg= Gm1m2/r2= (6.67x10^-11)(9.1x10^-31)(1.67x10^-27)/(10^-10)^2= 101.36x10^-49 Fe/Fg= 2 x 10^39

Electronic types neglect the force of gravity on electrons. To see why, compute the force of Earth's gravity on an electron and compare it with the force exerted on the electron by an electric field of magnitude 15000 V/m (a relatively small field). The mass and charge of an electron are given in the textbook.

Felec/Fgrav= 2.7 x 10^14 Felec= qE= (1.6 x 10^-19)(15000 V/m)= 2.4 x 10^-15 Fgrav= mg= (9.1 x 10^-31)(9.8 m/s2)= 8.9 x 10^-30 (2.4 x 10^-15)/(8.9 x 10^-30)= 2.7 x 10^14

A table rests on a floor without being pushed. How much friction acts on it? If the table is pushed horizontally with 110 N and doesn't slide, how much friction acts on it? If a horizontal push of 140 N causes it to slide at constant speed, how much friction acts on it?

Ffr = 0 N Ffr = 110 N Ffr = 140 N

What is the net force acting on a falling 1-kg ball if it encounters 7 N of air resistance?

Fnet= 2.8 N F= m*a △a= 9.81-7= 2.81 1*2.81= 2.8

What did Galileo discover in his legendary experiment on the Leaning Tower of Pisa?

Galileo found that a heavier stone does not fall significantly faster than a lighter one.

The wattage marked on a lightbulb is not an inherent property of the bulb, but depends on the voltage to which it is connected, usually 110 or 120 V. How many amperes flow through a 68-W bulb connected in a 110-V circuit?

I= 0.62 A P= VI ---- I= P/V 68 W/ 110 V= .618 A or .62 A

Using the formula, power = current × voltage, find the current drawn by a 1400-W toaster connected to 140 V. Then, using the equation current = voltage/resistance, find the resistance of the toaster.

I= 10 A---->1400/140= 10 A R= 14 Ω----> 140/10= 14 Ω

A toaster has a heating element of 18 Ω and is connected to a 120-V outlet. Determine the current drawn by the toaster.

I= 6.7 A 120/18= 6.666

Does a hot object contain internal energy or heat? Or do the two terms mean the same thing?

Internal energy. They are not two terms for the same thing.

What type of path does a moving object follow in the absence of a force?

It continues to move in a straight line at a constant speed.

As in the video, we apply a charge +Q to the half-shell that carries the electroscope. This time, we also apply a charge -Q to the other half-shell. When we bring the two halves together, we observe that the electroscope discharges, just as in the video. What does the electroscope needle do when you separate the two half-shells again?

It does not deflect at all.

What happens to the air pressure inside a balloon when it is squeezed to half its volume (assume constant temperature)?

It doubles.

What happens to the density of air in a party balloon when it is squeezed to half its volume (assume constant temperature)?

It doubles.

What can be said about the pressure of an inflated balloon?

It is equal to the atmospheric pressure.

What does the power company provide to our homes? Of what physical quantity is Hertz a unit of? What type of field causes the electrons to do what they do in the wire? What kind of current runs through the electric wiring in a home?

It provides energy to move the electrons. number of times per second that the electrons move back and forth in the wire electric field alternating current

A loaded ship arrives at the first freshwater lock of the Panama Canal, will it float higher or lower than in the open ocean?

It will float lower.

CH 7: Suppose our experimenter repeats his experiment on a planet more massive than Earth, where the acceleration due to gravity is g=30 m/s2. When he releases the ball from chin height without giving it a push, how will the ball's behavior differ from its behavior on Earth? Ignore friction and air resistance. (Select all that apply.)

It will take less time to return to the point from which it was released.

Calculate the kinetic energy of a 98-kg scooter moving at 16 m/s.

KE= 13000 J KE= (1/2)(m)(v^2) (.5)*(98)*(256)

Which generally expands more for an equal increase in temperature: solids or liquids?

Liquids generally expand more than solids.

Rank the six combinations of electric charges on the basis of the electric force acting on q1. Define forces pointing to the right as positive and forces pointing to the left as negative. Rank in increasing order by placing the most negative on the left and the most positive on the right. To rank items as equivalent, overlap them.

Most Negative: q1= +1nC, q2= +1nC, q3= +1nC q1= -1nC, q2= -1nC, q3= -1nC q1= +1nC, q2= +1nC, q3= -1nC q1= +1nC, q2= -1nC, q3= +1nC Most Positive: q1= +1nC, q2= -1nC, q3= -1nC q1= -1nC, q2= +1nC, q3= +1nC

If air drag is negligible, how does the horizontal component of velocity relate to Newton's first law of motion?

No force acts horizontally on the ball so the initial horizontal velocity remains constant as the ball moves through the air in accord with Newton's first law of inertia.

How much force is required to keep a moving hockey puck in motion on a perfectly frictionless surface?

No force is required for continued motion.

Select the correct equations that show that the gravitational potential energy of a 1000-kg boulder raised 3.0 m above ground level is 30,000 J.

PE=mgh=(1000kg)(10N/kg)(3.0m)=30,000J

Select the correct equations that show that when a 2.8-kg book is lifted 2.0 m its increase in gravitational potential energy is 56 J. (Don't forget g, which can be expressed in units N/kg, equivalent to m/s2.)

PE=mgh=(2.8kg)(10m/s2)(2.0m)=56J

Calculate the quantity of heat absorbed by 20 g of water that warms from 30∘C to 90∘C.

Q = 1200 cal m= 20g Cwater= 1 cal/g∘C △T= 90-60=30 Q= cm△T Q=(20 g)*(1 cal/g∘C)*(60 ∘C)= 1200 cal

You wish to warm 140 kg of water by 20 ∘C for your bath. Determine the amount of heat needed in kcal.

Q = 2800 kcal (1 cal/g) * (140) * (20)= 2800

Determine the number of calories to change 1.3 kg of 0∘C ice to 0∘C ice water. Determine the number of calories to change 1.3 kg of 0∘C ice water to 1.3 kg of 100∘C boiling water. Determine the number of calories to change 1.3 kg of 100∘C boiling water to 1.3 kg of 100∘C steam. Determine the number of calories to change 1.3 kg of 0∘C ice to 1.3 kg of 100∘C steam.

Q= 100 kcal Q= 130 kcal Q= 700 kcal Q= 940 kcal

You wish to warm 120 kg of water by 20∘C for your bath. Determine the amount of heat needed in kJkJ.

Q= 10000 kJ (4.19)*(2400)=10056

You wish to warm 140 kg of water by 20 ∘C for your bath. Determine the amount of heat needed in kJ

Q= 12000 kJ (11732 kJ) (4.19)*(2800)=11732

Two point charges are separated by 5.8 cm. The attractive force between them is 18 N. Suppose that the charges attracting each other have equal magnitude. Rearrange Coulomb's law and find the magnitude of each charge.

Q= 2.6 x 10^-6 C F= kq1q2/r2 q= r* squareroot of F/k q= .058 x squareroot of (18/(9x10^9) squareroot of 18/9x10^9= 4.47x10^-5 .058 x 4.47x10^-5= 2.6x10^-6

You wish to warm 120 kg of water by 20∘C for your bath. Determine the amount of heat needed in kcal.

Q= 2400 kcal (1 cal/g)*(120)*(20)=2400

In 1909, Robert Millikan was the first to find the charge of an electron in his now-famous oil-drop experiment. In that experiment tiny oil drops were sprayed into a uniform electric field between a horizontal pair of oppositely charged plates. The drops were observed with a magnifying eyepiece, and the electric field was adjusted so that the upward force on some negatively charged oil drops was just sufficient to balance the downward force of gravity. That is, when suspended, upward force qE just equaled mg. Millikan accurately measured the charges on many oil drops and found the values to be whole-number multiples of 1.6×10−19C, which turns out to be the charge of the electron. For this he won the Nobel Prize. (Figure 1) If a drop of mass 1.5×10−14kg remains stationary in an electric field of 4.59×105N/C, what is the charge of this drop? How many extra electrons are on this particular oil drop (given the presently known charge of the electron)?

Q= 3.2 x 10^-19 C [E= F/q---F=mg---F=(1.5x10^-14)(9.8)= 1.47x10^-13---(1.47x10^-13)/(4.59x10^5)= 3.2x10^-19 N= 2 (3.2x10^-19)/(1.6x10^-19)= 2

Determine the amount of heat required to increase the temperature of 50 g of water from 0∘C to 100∘C. The specific heat capacity for water is 1 cal/(g⋅∘C)

Q= 5000 cal m=50 g △T= 100-0=100 Cwater= 1 cal/g∘C Q=cm△T (50)(1)(100)=5000 cal

An electric iron connected to a 110-V source draws 10 A of current. Find the charge flow through the iron in 1 minute.

Q= 600 C P= VI Q= Pt P= (110 V)(10 A)= 1100 Q= (1100)(60 s)= 66000 J 66000/110= 600 C

Select the correct equations that show that 3000 cal are required to raise the temperature of 300 g of water from 22∘C to 32∘C. For the specific heat capacity c, use 1 cal/(g⋅∘C).

Q=cmΔT=(1cal/(g⋅∘C))(300g)(32∘C−22∘C)=3000cal

The specific heat capacity of steel is 450 J/kg⋅∘CJ/kg⋅∘C. Select the correct equations that show that the amount of heat needed to raise the temperature of a 10-kgkg piece of steel from 0 ∘C to 100 ∘C is 450,000 J. Select

Q=cmΔT=(450J/kg⋅∘C)(10kg)(100∘C−0∘C)=450,000J

Calculate the resultant of a horizontal vector with a magnitude of 5 units and a vertical vector with a magnitude of 12 units.

R= 13 units square root of (5^2)+(12^2)

Rearrange the equation, current = voltage/resistance, to express resistance in terms of current and voltage. Then solve the following: A certain device in a 100 V circuit has a current rating of 20 A. What is the resistance of the device (how many ohms)?

R= 5 Ω 100 V/ 20 A= 5 ohms

What is the relationship between wave speed and refraction?

Refraction is caused by the differences in wave speed in different materials.

What is the equivalent resistance of a pair of 7.5-Ω and 3.5-Ω resistors when connected in series? What is the equivalent resistance of a pair of 7.5-Ω and 3.5-Ω resistors when connected in parallel? When the series combination of 7.5-Ω and 3.5-Ω resistors is impressed with 12 volts, how much current is in it? When the parallel combination of 7.5-Ω and 3.5-Ω resistors is impressed with 12 volts, how much current is in it?

Req= 11 Ω-----> 7.5+3.5=11 Req= 2.4 Ω--> (1/7.5+1/3.5)= .41904-->1/.41904= 2.38 I= 1.1 A---> I= V/R---> 12/11= 1.09 A I= 5 A----> I= V/R---> 12/2.4= 5 A

Why does sound tend to bend as it grazes warm ground?

Speed of sound increases in the warmed air, so sound refracts upward.

Consider the situation in the figure below, where two charged rods are placed a distance d on either side of an aluminum can. What does the can do? Now, consider the situation shown in the figure below. What does the can do? Using the setup from the first question, imagine that you briefly touch the negatively charged rod to the can (assume that this rod is conducting for the sake of effect). You then hold the two rods at equal distances on either side of the can. What does the can do?

Stays still Stays still Rolls toward the positively charged rod

A 400 N scaffold supports two painters, one 500 N and the other 400 N. The reading in the left scale is 800 N.(Figure 1) What is the reading in the right-hand scale?

T= 500 N weight must equal tension 500+400+400= 1300 1300-800= 500 N

What happens the first time Dr. Hewitt lifts the bowling ball near his teeth and lets go? Why does the bowling ball behave the way it does the first time Dr. Hewitt lifts the bowling ball near his teeth and lets go? What happens the second time Dr. Hewitt lifts the bowling ball near his teeth and gives it a push? Why does the bowling ball behave as it does when Dr. Hewitt lifts it and gives it a push?

The ball returns to Dr. Hewitt, stopping almost exactly at the point where it was released. All of the initial energy of the ball was converted completely back to potential energy when the ball returned. The ball leaves Dr. Hewitt and returns to him, going past the point where it was released. The extra energy from the push is converted into kinetic energy, which is then converted into more potential energy at the end of the motion than the ball had when it was released.

What would happen to the two balls if one of them were kept positively charged and the charge on the other ball were slowly increased, making it more and more positive? What would happen to the two balls if one of them were kept positively charged and the charge on the other ball were slowly made increasingly negative? What would happen to the two balls if both of them had a non-neutral charge and you slowly increased the mass of the balls?

The balls would begin to move farther apart. The balls would begin to move closer together. The angle of the balls with respect to the vertical would decrease.

Why can't a boxer hit a piece of tissue paper in midair with the same amount of force with which he hits a heavy punching bag?

The boxer can only hit the tissue paper with a force as large as the tissue paper can exert on the boxer, and the low-mass tissue can only exert a weak force.

We repeat the experiment from the video, but this time we connect the wires in parallel rather than in series. Which wire will now dissipate the most heat?

The copper wire (resistance 0.1 Ω)

What happens to the current supplied by the battery when you add an identical bulb in parallel to the original bulb?(Figure 1) In a series circuit with two identical bulbs, what happens to the remaining bulb when one is replaced with a wire?(Figure 2) The brightness of identical bulbs varies depending on whether or not they are connected in series or parallel.(Figure 3) Rank in order, from brightest to dimmest, the identical bulbs A, B, and C. If two bulbs have the same brightness, place one on top of the other. From the following statements, identify those that are always true about simple series circuits or always true about simple parallel circuits as shown in (Figure 4). The bulbs in the circuits do not have the same resistance (i.e., RA≠RB≠RCRA≠RB≠RC). Drag each item to the appropriate bin. If an item does not describe a simple series or simple parallel circuit, drag it to the "neither" bin.

The current doubles. The remaining bulb gets brighter. BRIGHTEST: Bulb A MIDDLE: Bulb B, Bulb C Always true about simple circuits: The same current flows through each bulb in the circuit. Removing a bulb stops the current flow throughout the circuit. Adding a bulb makes the other bulbs dimmer. Always true about simple parallel circuits: There is the same voltage across each bulb in the circuit. Removing a bulb does not stop the current flow throughout... Neither: Adding a bulb makes the other bulbs brighter.

Which of the following describes the electric field produced by the positive charge? Consider the locations to the right, left, above, and below the positive charge, all 1 m away. For these four locations, the magnitude of the electric field is________________. The magnitude of the electric field 1 m away from the positive charge is ________________ the magnitude of the electric field 2 m away. If the field strength is E = 9 V/m a distance of 1 m from the charge, what is the field strength E a distance of 3 m from the charge? Remove the positive charge by dragging it back to the box at the bottom, and drag a negative charge (blue) toward the middle of the screen. Determine how the electric field is different from that of the positive charge. Which statement best describes the differences in the electric field due to a negative charge as compared to a positive charge? Where is the magnitude of the electric field roughly equal to zero (other than very far away from the charges)? Consider a point 0.5 m above the midpoint of the two charges. As you can verify by removing one of the positive charges, the electric field due to only one of the positive charges is about 18 V/m. What is the magnitude of the total electric field due to both charges at this location? The electric field at the midpoint is ________________. Measure the strength of the electric field 0.5 m directly above the midpoint as well as 1 m directly above. Does the strength of the electric field decrease as 1 over distance squared (1/r2)?

The electric field is directed radially away from the charge at all locations near the charge. the same. four times E= 1 V/m The electric field changes direction (now points radially inward), but the electric field strength does not change. The electric field is roughly zero near the midpoint of the two charges. 25 V/m directed to the right. No, it decreases more quickly with distance.

What general rule can you conclude about the force needed to keep an object in motion at a steady rate?

The force that you need to apply to keep an object moving at a steady rate is equal to the force resisting the motion of the object.

You exert a force on a ball when you toss it upward. How long does that force last after the ball leaves your hand?

The force you exert on the ball ceases as soon as contact with your hand ceases.

What happens to the frequency of the wave if you increase the wavelength, keeping the velocity of the wave constant? What happens to the frequency of the wave if you increase the wave velocity, keeping the wavelength of the wave constant? How can you double the frequency of a wave if you have control over both the wavelength and the wave velocity?

The frequency decreases. The frequency increases. You can either halve the wavelength, keeping the wave speed constant; or double the wave speed, keeping the wavelength constant.

Refer to Monkey Mo in (Figure 1). The rope makes an angle of 45 ∘ with the vertical. Monkey Mo is in equilibrium. How will the magnitudes of vectors S and mg compare?

The magnitude of S is equal to the magnitude of mg.

A glass marble is rubbed against a piece of silk. As a result the piece of fabric acquires extra electrons. What happens to the glass marble? Two glass marbles (1 and 2), each supported by a nylon thread, are rubbed against a piece of silk and then are placed near a third glass marble (3), also supported by a similar thread. Assuming that marble 3 has not been in contact with the piece of fabric, which of the following statements best describes the situation when the three marbles are brought together? To keep things simple in this Tutorial, we will ignore the effects of polarization and just focus on the overall charge of each object.

The marble has lost the same number of electrons acquired by the piece of silk. The marble acquires a positive charge and attracts the piece of silk. Marbles 1 and 2 repel each other, but no interaction occurs with marble 3.

Why when tuning a radio do you hear only one station at a time rather than hearing many stations at once?

The natural frequency of the electronics is tuned to resonate with the frequency of one station.

An object at rest cannot remain at rest unless which of the following holds? If a block is moving to the left at a constant velocity, what can one conclude? A block of mass 2kg is acted upon by two forces: 3N (directed to the left) and 4N (directed to the right). What can you say about the block's motion? A massive block is being pulled along a horizontal frictionless surface by a constant horizontal force. The block must be __________. Two forces, of magnitude 4N and 10N, are applied to an object. The relative direction of the forces is unknown. The net force acting on the object __________.

The net force acting on it is zero. The net force applied to the block is zero. It could be moving to the left, moving to the right, or be instantaneously at rest. moving with a constant nonzero acceleration cannot have a magnitude equal to 5N

What is the net force on a bag pulled down by gravity with 18 N and pulled upward by a rope with 18 N?

The net force is zero newtons.

What is the net force on an object that is pulled with 80 N to the right and 80 N to the left?

The net force is zero newtons.

What is the direction of the net force acting on the object at position A? What is the direction of the net force acting on the object at position B? What is the direction of the net force acting on the object at position C? Which of these situations describe the motion shown in the motion diagram at point A? Which of these situations describe the motion shown in the motion diagram at point B? Which of these situations describe the motion shown in the motion diagram at point C?

The net force is zero. to the left downward ad be g

What is the net force that acts on a 10-N falling object when it encounters 4 N of air resistance? When it encounters10 N of air resistance?

The net forces are 6 N and 0 N, respectively.

What is true about an object as its temperature increases?

The object's atoms gain kinetic and elastic potential energies.

A fresh breeze is felt on the shore with the sunset, because ground cools faster than the ocean. Which one has a higher specific heat?

The ocean

Which will undergo the greater rate of cooling--a redhot poker in a warm oven or a red-hot poker in a cold room (or do both cool at the same rate)?

The poker in the cold room cools fastest.

What happens to the pressure in all parts of a confined fluid if the pressure in one part is increased?

The pressure everywhere increases by the same amount.

If the volume of a confined gas is reduced 10 percent, how would the pressure of the gas change?

The pressure of the gas would increase by 10 percent.

What is the resultant of a pair of 1-N forces at right angles to each other?

The resultant is a force of 1.41 newtons in a direction bisecting the angle between the two vectors.

What is the result of a mirror image of a sound signal combining with the sound itself?

The sound is cancelled when added to its mirror image.

A sound wave is refracted when it moves from air to water, what happens to the speed of the wave front?

The speed of the wave front increases.

Why does a bimetallic strip bend with changes in temperature?

The two metals expand at different rates.

Describe the velocity and acceleration vectors of a projectile that is launched vertically up upon reaching its maximum height.

The velocity is zero and acceleration points down.

When you push against a wall, what pushes back?

The wall pushes back.

What specific force is accelerating Nellie (Figure 5.23 in the textbook) down the hill? (assume friction to be neglectable)

The x-component of the force of gravity

An object that is warmer than room temperature is placed in a room filled with room-temperature air. What is true about the object as its temperature decreases?

Thermal energy in the object is transferred to the surrounding air.

While sailing your small boat, the wind fades, and you are stranded in the middle of the lake. You try pushing hard on the mast, to no avail. Why?

These are internal forces to the system. There are no external forces acting on the system.

As a boxer hits the bag, the bag hits back at the boxer. Which force happens first?

They act at the same time.

A car accelerates from 10 m/s to 30 m/s in 4 seconds, and then slows down to 20 m/s in 2 seconds. What can you say about the net force acting on the car for both intervals?

They are equal and opposite.

An energy of 0.17 J is stored atop the metal sphere of a Van de Graaff generator. A spark carrying 1.0 microcoulomb (10-6 C) discharges the sphere. Find the sphere's potential relative to ground.

V= 170000 V V= J/C

A merchant in Katmandu sells you a solid gold 1.00-kg statue for a very reasonable price. When you get home, you wonder if you got a bargain, so you lower the statue into a container of water and measure the volume of displaced water. Find the volume of water that will be displaced for pure gold.

V= 51.8 cm3 density of gold is 19.3 g/cm3 1 kg= 1000 g volume= mass/density 1000/19.3= 51.8 cm3

Henry Heavyweight weighs 1290 N and stands on a pair of bathroom scales so that first scale reads twice as much as the second one. What are the scale readings?

W1, W2= 860, 430 N equation 1: scale 1+ scale 2= 1290 equation 2: scale 1= 2 * scale 2 equation 1 becomes (2 * scale 2)+scale 2= 1290 So, 3 * scale 2= 1290 1290/3= 430 1290-430= 860

Calculate the work done when a force of 12 N moves a book 1.5 m. (1 N⋅m = 1 J)

W= 18 J

The sketch in (Figure 1) shows a painter's scaffold in mechanical equilibrium. The painter weighs 500 N, and the tensions in each rope are 400 N. What is the weight of the scaffold?

W= 300 N 400+400= 800 800-500=300 N

Lucy Lightfoot stands with one foot on one bathroom scale and her other foot on a second bathroom scale. Each scale reads 370 N. What is Lucy's weight?

W= 740 N

If the penny experiences almost no air resistance as it falls (very unrealistic!), find its kinetic energy just before striking the sidewalk.

W= 9.5 J W= mgh 2.5 g= .0025 kg (.0025)*(9.81)*(381)= 9.34

Calculate the work done in lifting a 450-N barbell 2.2 m above the floor. What is the gain of potential energy of the barbell when it is lifted to this height?

W= 990 J ΔU = 990 J

Select the correct equations that show that the kinetic energy of a 1.0-kg hamster running at 6.0 m/s is 18 J. [1 J is equivalent to 1 kg(m/s)2]

W=12mv2=12(1.0kg)(6.0m/s)2=18J

Select the correct equations that show that a 8100000-J change in kinetic energy occurs for an airplane that is moved 900 m in takeoff by a sustained force of 9000 N.

W=Fd=(9000N)(900m)=8100000J

Select the correct equations that show that 16 J of work is done when a 2.0-kg block of ice is moved from rest to a speed of 4.0 m/s.

W=mv2/2=(2.0kg)(4.0m/s)2/2=16J

Why does all the water in a lake have to be cooled to 4∘C before the surface water can be cooled below 4∘C?

When water is cooled to 4∘C, it sinks and deeper, warmer, water rises to the surface.

Earth pulls down on you with a gravitational force that you call your weight. Do you pull up on Earth with the same amount of force?

Yes, you pull up on Earth with the same force.

If a certain material heats up quickly and cools down quickly, the material has ___________.

a low specific heat

Heat always flows spontaneously from ___________.

a warmer to a cooler object

a) What is the difference in the speed of sound on a warm day versus on a cold day? b) Why did the campers in Dr. Hewitt's story hear the sound of the campers across the lake more clearly at night than during the day? c) How does the direction of sound travel compare to the shapes of the sound waves? d) How does the cooler air above the lake affect the movement of sound at night? e)How do the waves of sound travel on the night that produces the temperature inversion, and why?

a) It is faster on a warm day and slower on a cold day. b) The temperature change from cold at the surface to warm at the top changed the shape of the sound waves. c) The sound is at right angles to the waves. d) Because it is colder just above the surface and warmer higher above, the sound wave is refracted toward the ground. e)The waves bend toward the ground because it is warmer above and colder lower below, and waves travel more slowly through the colder air.

a) Given a wave of a particular wavelength and amplitude, what must be the amplitude, wavelength, and phase change of a wave you add to this wave to create a wave of twice the amplitude? b) Given a wave of a particular wavelength and amplitude, what must be the amplitude, wavelength, and phase change of a wave you add to the existing wave to completely destroy it? c) For maximum constructive interference between two waves, how must their crests and troughs align with each other? d) For complete destructive interference between two waves, how must their crests and troughs align with each other?

a) The added wave must have the same amplitude, the same wavelength, and a phase difference of 0 degrees with respect to the original wave. b) The added wave must have the same amplitude, the same wavelength, and a phase difference of 180 degrees with respect to the original wave. c) The crests and troughs of one wave should align with the crests and troughs of the other wave respectively. d) The crests and troughs of one wave should align with the troughs and crests of the other wave respectively.

a) When a car veers off the road such that the left front wheel goes off the pavement into the gravel before the right wheel, what will happen to the car, and why? b) What is the relationship between the direction of traveling rays of light and the line representing the wave crests? c) What happens to the speed of light waves when they enter water from air? d) What happens to the wavelength and frequency of the light waves as they enter water from air?

a) The car will tend to turn to the left. Because the left wheel hits the gravel first and slows down before the right wheel, the right wheel covers a greater distance, causing the car to turn to the left. b) The direction of the rays of light is perpendicular to the line representing the wave crests. c) The speed decreases. d) Wavelength decreases, and frequency will stay the same.

a) After the block is released from x=A, it will b) If the period is doubled, the frequency is c) An oscillating object takes 0.10 s to complete one cycle; that is, its period is 0.10 s. What is its frequency f? d) If the frequency is 40 Hz, what is the period T ? e) Which points on the x axis are located a distance A from the equilibrium position? f) Suppose that the period is T. Which of the following points on the t axis are separated by the time interval T? g) What is the period T ? h) How much time t does the block take to travel from the point of maximum displacement to the opposite point of maximum displacement? i) What distance d does the object cover during one period of oscillation? j) What distance d does the object cover between the moments labeled K and N on the graph?

a) move to the left until it reaches x=−A and then begin to move to the right. b) halved. c) f= 10 Hz d) T= .025 s e) both R and Q f) K and P g) T= .02 s h) t= .01 s i) d= .48 m j) d= .36 m

a) In an insulated vessel, a quantity of hot water at temperature T1 is mixed with a different quantity of cold water at temperature T2. After equilibrium is established, the vessel contains __________. b) The final temperature of the water is __________. c) Water with a mass of 0.500 kg at 15.0∘C is mixed with 0.800 kg of water at 35.0∘C. What is the final temperature Tf of the mixture? d) In an insulated container, liquid water is mixed with ice. What can you conclude about the phases present in the container when equilibrium is established? e) In an insulated container, 0.50 kg of water at 80∘C is mixed with 0.050 kg of ice at −5.0∘C. After a while, all the ice melts, leaving only the water. Find the final temperature Tf of the water. The freezing point of water is 0∘C. f) You are mixing water with ice in an insulated container. The temperature of the ice is initially below its freezing point. The following are given: the amount of heat absorbed by the ice if heated to its melting point: 400 J, the amount of heat absorbed by the ice if it all melts (which includes the heat needed to bring the ice to its melting point): 2100 J, the amount of heat given off by the water if cooled to its freezing point: 2400 J, and the amount of heat given off by the water if it all freezes (which includes the heat needed to bring the water to its freezing point): 5200 J. Based on this information, at equilibrium, which phases are present? g) You are mixing water with ice in an insulated container. The temperature of the ice is initially below its freezing point. The following are given: the amount of heat absorbed by the ice if heated to its melting point: 400 J, the amount of heat absorbed by the ice if it all melts (which includes the heat needed to bring the ice to its melting point): 2100 J, the amount of heat given off by the water if cooled to its freezing point: 1800 J, and the amount of heat given off by the water if it all freezes (which includes the heat needed to bring the water to its freezing point): 5200 J. Based on this information, at equilibrium, which phases are present? h)You are mixing water with ice in an insulated container. The temperature of the ice is initially below its freezing point. The following are given: the amount of heat absorbed by the ice if heated to its melting point: 6400 J, the amount of heat absorbed by the ice if it all melts (which includes the heat needed to bring the ice to its melting point): 14,100 J, the amount of heat given off by the water if cooled to its freezing point: 1800 J, and the amount of heat given off by the water if it all freezes (which includes the heat needed to bring the water to its freezing point): 5200 J. Based on this information, at equilibrium, which phases are present? i) In an insulated container, 0.800 kg of water at 40.0∘C is mixed with 0.500 kg of ice at −15.0∘C. Find the final temperature Tf of the system. The freezing point of water is 0∘C.

a) water only b) between T1 and T2 c) Tf = 27.3 C m1= .800 kg T1= 35 C m2= .500 kg. T2= 15 C temp change m1= cm△T: (1)*(.800)*(35)= 28 temp change m2= cm△T: (1)*(.500)*(15)= 7.5 28+7.5=35.5----- m1: (1)*(.8)=.8 m2: (1)*(.5)=.5 .5+.8= 1.3 35.5/1.3= 27.3 C d) There is no way of knowing the phase composition without more information. e) Tf = 65.45 C ice: .05 kg= 50 g water: .50 kg= 500 g (miL)+(mi*ci*△T)=mw*c*△T (50*80)+(50*1*Tf)=(500)*(1)*(80-Tf) cancel out the 50: 80+Tf= 800-10Tf 11Tf=720 ----- Tf= 65.45 f) water only Since 2100 J is less than 2400 J , the ice would completely melt before the water reaches its freezing point. The final temperature of the mix is above 0∘C . g) both ice and water Since 2100 J is more than 1800 J, the ice would not completely melt by the time the water reaches its freezing point. However, since 400 J is less than 1800 J, the ice will, indeed, melt partially. The final temperature of the mix is 0∘C. h) ice only Since 6400 J is more than 5200 J, the ice would not even begin to melt by the time all the water freezes. The final temperature of the mix is below 0∘C. i) Tf = 0∘C

A ball is tossed with enough speed straight up so that it is in the air for several seconds. a) What is the velocity of the ball when it reaches its highest point? b) What is its velocity 1 s before it reaches its highest point? c) What is the change in its velocity during this 1-s interval? d) What is its velocity 1 s after it reaches its highest point? e) What is the change in velocity during this 1-s interval? f) What is the change in velocity during the 2-s interval? (Careful!) g) What is the acceleration of the ball during any of these time intervals and at the moment the ball has zero velocity?

a) v= 0 m/s b) v= 10 m/s c) △v= -10 m/s d) v= -10 m/s e) △v= -10 m/s f) △v= -20 m/s g) a= -10 m/s2

a)When the bug is stationary and creating waves, how does the frequency of the wave some distance away from the bug compare with the frequency of the vibration of the bug? b)When the bug that is creating waves swims in the direction of the waves, how does the speed of the wave some distance away in front of the bug compare with the speed of the wave created by a stationary bug? c)When the bug that is creating waves swims forward, how does the frequency of the wave some distance away in front of the bug compare with the frequency of the wave produced by a stationary bug? d)When the bug that is creating waves swims forward, how does the frequency of the wave some distance away behind the bug compare with the frequency produced by a stationary bug?

a)The frequency of the wave some distance away is equal to the frequency of the vibration of the bug. b)The speed of the wave some distance away is equal to the speed of the wave due to a stationary bug. c)The frequency of the wave some distance away in front of the bug is greater than the frequency produced by a stationary bug. d)The frequency of the wave some distance away behind the bug is less than the frequency of the wave produced by a stationary bug.

Calculate the acceleration of a 350000-kg jumbo jet just before takeoff when the thrust on the aircraft is 80000 N.

a= .23 m/s2 a= F/m 80,000/350,000= .228

Calculate the acceleration of a 1700-kg, single-engine airplane as it begins its takeoff with an engine thrust of 600 N. (FYI: The unit N/kg is equivalent to m/s2.)

a= .35 m/s2 a= F/m

A 38000 kg business jet takes off when the thrust for each of its two engines is 20000 N. Find its acceleration.

a= 1.1 m/s2 a= F/m Since the jet has two engines: net force= 40,000 N 20,000*2=40,000 40,000/38,000= 1.05

A car takes 10 s to go from v = 0 m/s to v = 22 m/s at constant acceleration. If you wish to find the distance traveled using the equation d=12at2, what value should you use for a?

a= 2.2 m/s2 acceleration= △v/t Vi= 0 Vf= 22 △v= 22 22/10= 2.2

A boxer punches a sheet of paper in midair and brings it from rest up to a speed of 21 m/s in 0.060 s. What is the acceleration imparted to the paper? If the mass of the paper is 0.003 kg, what force does the boxer exert on it? How much force does the paper exert on the boxer?

a= 350 m/s2 acceleration= △v/t----> (21-0)/.06= 250 F= 1.05 N Force= ma---->0.003*350= 1.05 F= 1.05 N

Alex, who has a mass of 120 kg, is skateboarding at 8.5 m/s when he smacks into a brick wall and comes to a dead stop in 0.20 s. What is the magnitude of his deceleration? What is the force of impact?

a= 43 m/s2 a= △v/t----> (8.5-0)/.2= 42.5 F= 5100 N F=m*a-----> 120*42.5= 5100

Select the correct equations that show that the acceleration of a car is 6 km/(h⋅s) when starting from rest to 60 km/h in 10 s.

a=Δv/Δt=(60km/h)/(10s)=6km/(h⋅s)

When the temperature of a strip of iron is increased, the length of the strip ___________.

also increases

Rank the beat frequency from highest to lowest for the following pairs of sounds: (a) 125 Hz, 123 Hz (b) 453 Hz, 458 Hz (c) 453 Hz, 456 Hz (d) 328 Hz, 329 Hz

b, c, a, d

How can you use the graph of velocity versus time to estimate the acceleration of the ball? How does the distance traveled by the ball in the second half second compare with the distance traveled by the ball in the first half second? Why does the distance traveled by the ball in each half second after it is released change in the way in which it does?

by estimating the value of the slope of the graph It increases. Gravity is pulling down on the ball, so it accelerates down at a steady rate.

Three blocks of metal at the same temperature are placed on a hot stove. Their specific heat capacities are listed below. Steel, 450 J/(kg⋅∘C)J/(kg⋅∘C) Aluminum, 910 J/(kg⋅∘C)J/(kg⋅∘C) Copper, 390 J/(kg⋅∘C)J/(kg⋅∘C) Rank them from greatest to least in how quickly each warms up.

c, a, b

To obtain the resultant from two vectors we have to _____.

consider their respective directions and determine whether to add (same direction), subtract (opposite direction), or use the parallelogram method (if at an angle)

You watch distant Sally Homemaker driving nails into a front porch at a regular rate of 1 stroke per second. You hear the sound of the blows exactly synchronized with the blows you see. And then you hear one more blow after you see the hammering stop. Calculate the distance of Sally from you.

d= 330 m d=v*t 330*1= 330

Imagine a Rip van Winkle type who lives in the mountains. Just before going to sleep, he yells, "WAKE UP", and the sound echoes off the nearest mountain and returns 7.6 hours later. Find the distance between Rip and the imaginary mountain.

d= 4,514,400 m d=v*t velocity of air sound= 330 m/s time to get there and back= 7.6 hours. 7.6*60= 456 minutes. 456*60= 27,360 seconds. Divide 27,360 by 2 because the distance is only a one way shot not two, like the time. 27,360/2= 13,680 sec 330*13,680= 4,514,400 m

What beat frequencies are possible with tuning forks of frequencies 258, 263, and 267 Hz?

f1,f2,f3 = 4,5,9 Hz 267-263= 4 263-258= 5 267-258= 9

A weight suspended from a spring is seen to bob up and down over a distance of 18 cm twice each second. What is its frequency? What is its period? What is its amplitude?

f= 2 Hz 2 bobs/second= 2 Hz T= .50 s period is time taken to complete oscillation. 2 oscillations take 1 second. So, 1 oscillation takes .5 s A= 9 cm amplitude is from highest wave point to the middle of the wave. So, A= 18/2= 9 cm

When a sound source approaches a stationary listener, the listener experiences an increase in sound _________.

frequency

From greatest to least, rank the energy needed for these phase changes for equal amounts of water.

from boiling water to steam from ice-water to boiling water from ice to ice-water

If you pull one end of the rope 1 m downward with a 50-N force, find the height you can lift a 250-N load.

h= .20 m work input= work output Input= 50*1= 50 N Output= 50= 250*d----> d= 50/250= .2 m

Find the height from which a block of ice should ideally be dropped to completely melt if it falls without air drag.[Hint: Equate the joules of gravitational potential energy to the product of the mass of ice and its heat of fusion (in SI units, 335,000 J/kg).] Does the answer depend on mass?

h= 34 km no

The weight of the atmosphere above 1 square meter of Earth's surface is about 100,000 N. Density, of course, becomes less with altitude. If the density of air were a constant 1.2 kg/m3, calculate where the top of the atmosphere would be.

h=8330 m W= 100,000 N A= 1 m2 Density of air= 1.2 kg/m3 W=mg---->m=W/g----> 100,000/9.81= 10193 density= m/V--->V=A*h--->density= m/(A*h) h=m/(A*density)--->10193/1*1.2= 8494 m

An object is in mechanical equilibrium only when _____.

it is at rest or moving with a constant speed in a straight line the net force acting on the object is zero

A grocery bag can withstand 100 N of force before it rips apart. How many kilograms of apples can it safely hold?

m= 10 kg N= ma 100= m*9.81 100/9.81= 10.1

The quantity of heat with temperature change is Q=cmΔT. For a change of phase of water it is Q=mL, where Lf is the heat of fusion, 80 cal/g, and Lv is the heat of vaporization, 540 cal/g. Find the mass of 0∘C ice that 6.0 g of 100∘C steam will completely melt.

m= 48 g

A 48-g chunk of 78 ∘C iron is dropped into a cavity in a very large block of ice at 0∘C. Find what mass of ice will melt. (The specific heat capacity of iron is 0.11 cal/g∘C.)

m= 5.1 g Temp change: cm△T: (.11)*(48)*(78)= 411.84 cal phase change: Q=mL----> m=Q/L: 411.84/80= 5.1

The heat of vaporization of ethyl alcohol is about 200 cal/g If 2.8 kg of this fluid were allowed to vaporize in a refrigerator, find what mass of ice would be formed from 0∘C water.

m= 7 kg 2.8kg= 2800 g Q= mL ------> (200)*(2800)=560,000 cal 560,000/80= 7000 g or 7 kg

Find the mass of 0∘C ice that 9.0 g of 100∘C steam will completely melt.

m= 72 g Q= (mLv)+(cm△T) (9*540)+(9*1*100)= 5760 cal Q= mi*Li 5760=mi*80-----> 5670/80= 72 g

Resonance occurs when forced vibration _________.

matches natural frequency

A basketball floats in various liquids. Rank the percentage of its volume above the water line, from most to least for the following: Floating in

mercury, saltwater, freshwater

Rank the volume of air in the glass, from greatest to least, when it is held A. near the surface as shown. B. 1 m beneath the surface. C. 2 m beneath the surface.

near the surface as shown 1 m beneath the surface 2 m beneath the surface

Melting and freezing are _________.

opposite processes

The team to win in a tug-of-war is the team that _______.

pushes harder on the floor while holding the rope

Compared with the force exerted on each trailer, rank the magnitude of force each trailer exerts on the van. (Or are all pairs of forces equal in magnitude?)

put all in middle

A 100-kg tool box is in locations A, B, and C (Figure 1). Rank from greatest to least the masses of the 100-kg box. Rank from greatest to least the weights of the 100-kg box.

put all in the middle C (Jupiter), A (Earth), B (Moon)

Three pucks, A, B, and C, are shown sliding across ice at the noted speeds. Air and ice friction forces are negligible. Rank the force needed to keep them moving, from greatest to least. Rank the force needed to stop them in the same time interval, from greatest to least.

put them all in the middle 6 m/s, 4 m/s, 2 m/s

What is the total surface charge qint on the interior surface of the conductor (i.e., on the wall of the cavity)? What is the total surface charge qext on the exterior surface of the conductor? What is the magnitude Eint of the electric field inside the cavity as a function of the distance r from the point charge? Let k, as usual, denote 14πϵ0. What is the electric field Eext outside the conductor? The total surface charge on the wall of the cavity, qint: The total surface charge on the exterior of the conductor, qext: The electric field within the cavity, Ecav: The electric field outside the conductor, Eext:

qint= -q qext= q kq/r2 the same as the field produced by a point charge q located at the center of the sphere would not change would not change would not change would change

Heat travels from the Sun to Earth by the process of ___________.

radiation

When watching distant fireworks you note a 2 second delay between seeing and hearing a burst. Estimate a distance between your and fireworks.

s= 660 m d=v*t velocity= 330 time= 2 sec 330*2=660 m

With the "Pulleys" slider set at 1, predict the minimum force needed to hoist the load. You may want to pay attention to the provided force diagram -- in particular the size of the upward force compared to the downward force. How does the minimum force needed to hoist a load change as you increase the number of pulleys from one to two, then three, then four? How does the travel distance of the load change as you increase the number of pulleys from one to two, then three, then four?

slightly greater than 250 N The minimum force needed to hoist the load becomes half, then one-third, then one-fourth. The travel distance of the load becomes half, then one-third, then one-fourth.

Which word in the statement of this problem allows you to assume that the table is frictionless? Suppose the potential energy of the block at the table is given by mgh/3. This implies that the chosen zero level of potential energy is __________. If the zero level is a distance 2h/3 above the floor, what is the potential energy U of the block on the floor? Considering that the potential energy of the block at the table is mgh/3 and that on the floor is −2mgh/3, what is the change in potential energy ΔU of the block if it is moved from the table to the floor? Which most simplified form of the law of conservation of energy describes the motion of the block when it slides from the top of the table to the bottom of the ramp? As the block slides down the ramp, what happens to its kinetic energy K, potential energy U, and total mechanical energy E? Using conservation of energy, find the speed vb of the block at the bottom of the ramp. Which most simplified form of the law of conservation of energy describes the motion of the block as it slides on the floor from the bottom of the ramp to the moment it stops? As the block slides across the floor, what happens to its kinetic energy K, potential energy U, and total mechanical energy E? What force is responsible for the decrease in the mechanical energy of the block? Find the amount of energy E dissipated by friction by the time the block stops.

smooth a distance 2h/3 above the floor U= -2mgh/3 ΔU= -mgh 12mv2i+mghi=12mv2f+mghf12mvi2+mghi=12mvf2+mghf K increases;U decreases;E stays the same vb =(v2+2gh) 12mv2i+Wnc=012mvi2+Wnc=0 K decreases;U stays the same;E decreases friction E = 0.5mv2+mgh

Surprisingly, very few athletes can jump more than 2 feet (0.6 m) straight up. Use d=12gt2 and solve for the time one spends moving upward in a 0.6-m vertical jump. Then double it for the "hang time"--the time one's feet are off the ground.

t= 0.7 s d= (1/2)(g)(t^2) rearrange that as: square root of (2d)/g square root of (2*0.6)/9.81= .35 Now double it, .35*2= .7 s

The total charge that an automobile battery can supply without being recharged is given in terms of ampere-hours. A typical 12-V battery has a rating of 60 ampere-hours (60 A for 1 h, 30 A for 2 h, and so on). Suppose that you forget to turn the headlamps off in your parked automobile. If each of the two headlamps draws 1.5 A, how long will it be before your battery is "dead"?

t= 20 h Time= 60 A/ (2 x 1.5 A) * 1 h= 20 h

The force that propels a rocket is that provided by _______.

the expelled gas pushing on the rocket

Resonance occurs when forced vibrations match _________.

the natural frequency

Drag a battery into the construction panel, and use the voltmeter to determine which end of the battery is the positive terminal. The positive terminal has a higher potential than the negative terminal (recall that the voltmeter measures the potential difference between the red probe and the black probe). Which end of the battery is the positive terminal? Construct a circuit containing one battery, one resistor, and wire to close the circuit. The order and orientation doesn't matter, but it should look something like the figure below. You can show the values of the components by clicking the Values checkbox in the display at the upper-right corner of the panel. Use the default values of the battery and resistor. In what direction is the (conventional) current flowing through the circuit? Recall that current is the flow of positive charge. Use the noncontact ammeter to measure the current flowing through the circuit. What is the current? For the circuit in the previous part, the current flowing in the wire between the positive terminal of the battery and the resistor is ___________ the current flowing between the resistor and the negative terminal of the battery. Double the resistance of the resistor by changing it from 10 Ω to 20 Ω. What happens to the current flowing through the circuit? For the circuit containing one resistor and one battery, what happens to the current if the voltage is doubled? For the circuit containing one resistor and one battery, what happens to the current if the voltage is tripled and the resistance is doubled? What is the voltage reading across the resistor, as shown in the figure below? A light bulb is basically a resistor that gets so hot that it glows, emitting light. For this tutorial we will assume the resistor in the light bulb is ohmic (that means Ohm's law applies to the resistor). The rate of energy emitted by the light bulb is its output power, commonly referred to as luminosity (brighter means more luminous). Hook up a light bulb to a 5-V battery. Right-click (or control-click) on the light bulb, and change its resistance. How does the brightness of the light bulb depend on its resistance? In Part H, you discovered that the luminosity of a light bulb increases if the current increases. The rate at which electric potential energy is converted into heat depends on the current flowing through the bulb and the voltage across the bulb. This energy is supplied by the battery. Mathematically, the luminosity PP of the light bulb is given by P=ΔVIP=ΔVI, where ΔVΔV is the voltage across the bulb and II is the current.What happens to the luminosity of the light bulb if the voltage of the battery is doubled? (Note that the PhET simulation does not display a numerical value for the luminosity, so you should use the relationship between the luminosity, the voltage across the bulb, and the current.)

the orange end The current flows from the positive terminal, through the wires and resistor, and into the negative terminal. 0.9 A equal to The current decreases by a factor of two. The current increases by a factor of two. The current increases. 9.0 V The light bulb gets dimmer as the resistance is increased. The luminosity increases by a factor of four.

Construct a circuit containing a battery, a resistor, a switch, and a capacitor (all in series), as shown in the figure below. Be sure the switch is open (which stops current through the switch) before you connect the entire circuit. Now, close the switch and monitor the resulting current through the circuit. After the switch is closed, Long after the switch is closed and the current becomes very small, what is the voltage difference across the capacitor? Now, repeat the experiment several times to investigate how the amount of time to charge the capacitor (resulting in a voltage difference equal to the emf of the battery) depends on the capacitance of the capacitor and the resistance of the resistor. Each time you repeat the experiment, you first need to open the switch and click on the capacitor to select the Discharge Capacitor icon. The amount of time __________ if the resistance is increased and __________ if the capacitance is increased. Now, we'll add a bulb in parallel to the capacitor. Build the circuit shown in the figure below (you'll need to close the switch to charge the capacitor and light the bulb). What happens to the luminosity (or brightness) of the bulb when the switch is then opened?

there is initially a current, but it decreases with time and eventually stops. The same as the emf of the battery increases / increases The luminosity is initially the same as before the switch is closed, but then gradually fades to zero.

You are holding a positive charge and there are positive charges of equal magnitude 1 m to your north and 1 m to your east. What is the direction of the force on the charge you are holding? Four +2 μC charges are placed at the positions (10 cm, 0 cm), (−10 cm, 0 cm), (0 cm, 10 cm), and (0 cm, −10 cm) such that they form a diamond shape centered on the origin. A charge of +5 μC is placed at the origin. If the force between a +2 μC and a +5 μC charge separated by 10 cm has a magnitude of 9 N, which of the following can we say about the force on the +5 μC charge at the origin in this case? A charge of +0.001 C is 1 m to your right and another charge of +1000 C is 1 m to your left. You are holding a charge of −1 CC. Which of the following statements is/are true? If three uncharged styrofoam balls are placed together and agitated so that one gains +3 C of charge and another gains +4 C of charge, how much charge must there be on the third one?

to the southwest The force on the charge at the origin is 0. The magnitude of the force on the charge you are holding would be the same if it were +1 C instead of −1 C. & The force on the charge you are holding from the charge on your left is 1,000,000 times as large as the force from the charge on your right. -7 C

From the initial PE of the banana converting to KE, find the speed of the banana just before hitting the water.

v = √2gh

What is the instantaneous velocity of a freely falling object 5.0 s after it is released from a position of rest? What is its average velocity during this 5.0-s interval? How far will it fall during this time?

v= -49 m/s velocity= g*t ----> 5 * 9.81 (falling down so negative) Vavr= -25 m/s average velocity= (Vf+Vi)/2 ----> (-49+0)/2= -24.5 d= 120 m distance= (1/2)*(g)*(t^2)----> (1/2)*(9.81)*(25)= 122.6

What is the speed over the ground of a mosquito flying 2 m/s relative to the air against a 2 m/s headwind?

v= 0 m/s 2 m/s- 2 m/s = 0

What is the speed over the ground of a mosquito flying 1.1 m/s relative to the air caught in a 1.1 m/s right-angle crosswind?

v= 1.6 m/s For a right angle, use square root of (a^2+b^2) (1.1^2)= 1.21 1.21+1.21= 2.42 square root of 2.42= 1.6

What will be the airplane speed when flying at 180 km/h and encountering a 80-km/h crosswind (at a right angle to the airplane)?

v= 200 km/h

What is the speed of a water wave of frequency 2.0 Hz and wavelength of 1.8 m?

v= 3.6 m/s v= λ*f 1.8*2= 3.6

Whenever a (non-zero) net force acts on an object, there is a change in the object's _________.

velocity

What is the flow of current proportional to? A pipe is filled with water, and there is a piston at each end. If you apply unequal pressures at the two pistons, which way will the water flow in the pipe? What happens to a lamp when you take both ends of the wire connected to it and hold them to the same side of the 12-volt terminal of battery, and why? What happens when you have a voltage difference between the two ends of the lamp, and why?

voltage difference between the two ends of the wire Water will flow from the piston with the higher pressure to the piston with the lower pressure. The lamp does not light up because there is no voltage difference applied across it. The lamp lights up because there is a voltage difference applied to it.

Calculate the weight in newtons of a 64-kg person.

w= 640 N w=m*g

Three liquid samples, each having a mass of 1.0 kg, are warmed from room temperature to 50∘C using identical burners and then removed from the burners and allowed to cool. Rank the liquids according to the heat released from each as they cool back down to room temperature.

water, milk, vegetable oil

What is the wavelength of a 280-Hz tone in room-temperature air?

λ1= 1.18 m room temp. air speed= 330 m/s frequency= 280 Hz λ= v/f 330/280= 1.18

What is the wavelength of a 28,000-Hz ultrasonic wave in the same air?

λ2= .012 m room temp speed= 330 freq.= 28,000 Hz 330/28000= 0.0117

A mosquito flaps its wings 400 vibrations per second, which produces the annoying 400-Hz buzz. Given that the speed of sound is 340 m/s, how far does the sound travel between wing beats? In other words, find the wavelength of the mosquito's sound.

λ= .85 m λ= v/f velocity (v)= 340 frequency (f)= 400 340/400= .85

For years, marine scientists were mystified by sound waves detected by underwater microphones in the Pacific Ocean. These so-called T-waves were among the purest sounds in nature. Eventually they traced the source to underwater volcanoes, whose rising columns of bubbles resonated like organ pipes. What is the wavelength of a typical T-wave whose frequency is 7.00 Hz? (The speed of sound in seawater is 1530 m/s.)

λ= 218.57 m

A grunting porpoise emits sound at 57.0 Hz. What is the wavelength of this sound in water, where the speed of sound is 1530 m/s?

λ= 26.8 m λ= distance d=v*t Time is 1/frequency----- 1/57= .0175 .0175*1530= 26.8

The top floor of a building is 26 m above the basement. Calculate the difference between water pressure in the basement and the water pressure on the top floor.

△P= 260 kPa Pressure= density*g*d Density of water= 1000 kg/m3 (1000)*(9.81)*(26)= 255060 Pa

A 14-kg iron ball is dropped onto a pavement from a height of 130 m. If half of the heat generated goes into warming the ball, find the temperature increase of the ball. (In SI units, the specific heat capacity of iron is 450 J/kg⋅∘C) Is the answer the same for a ball of any mass?

△T= 1.4 ∘C 1/2PE= Heat 1/2mgh= cm△T (1/2)*(14)*(9.81)*(130)= (450)*(14)*(△T) 8927.1= 6300*△T △T= 8927.1/6300= 1.4 yes