PHYS221 Final Exam

When a sample of 0ºC water is heated, it first A. Expands then contracts. B. Contracts then expands. C. remains unchanged. D. Continuously expands. E. not enough information.

B. Contracts then expands.

Which has the higher specific heat, water or land? A. Water. B. Land. C. Both of the above are the same. D. None of the above.

A. Water.

A traffic light of weight w hangs from two lightweight cables as shown. Each cable hangs at a 450angle from the vertical. What is the tension in each cable? A. w/2 B. w/√2 C. w D. w√2 E. 2w

B. w/√2

How many significant figures are in the number 120.070? A. four B. five C. six D. Three

C. six

A brick weighs 50.0 N, and measures 30.0 cm × 10.0 cm × 4.00 cm. What is the maximum pressure it can exert on a horizontal surface due to its weight? A) 1.25 kPa B) 1.25 Pa C) 12.5 Pa D) 12.5 kPa

D) 12.5 kPa

In the constellation Orion, you can easily observe thedifference between the reddish looking starBetelgeuse and the bluish looking star Rigel. Which of the two has the hotter surface temperature? 1. Betelgeuse 2. Rigel 3. They have the same surface temperature, since they are in the same constellation. 4. There is no way to tell since we do not know the exact distance to those stars.

2. Rigel

Your dryer is broken, so you have to hang your wet clothes from the washing machine outside to dry. Under which conditions would your clothes dry fastest? 1. When it is 50°F with 50% relative humidity. 2. When it is 75°F with 50% relative humidity. 3. They will dry at the same rate at any temperature with 50% relative humidity. 4. The clothes will not dry with 50% relative humidity.

2. When it is 75°F with 50% relative humidity.

Referring to the graph below, which phase has the smallest specific heat capacity? 1.Solid 2.Liquid 3.Gas 4.They all have the same heat capacity.

3. Gas

When a fan is turned off, its angular speed decreases from 10 rad/s to 6.3 rad/s in 5.0 s. What is the magnitude of the average angular acceleration of the fan? A) 0.74 rad/s2 B) 0.37 rad/s2 C) 11 rad/s2 D) 0.86 rad/s2 E) 1.2 rad/s2

A) 0.74 rad/s2

The lug nuts on a car wheel require tightening to a torque of 90 N · m. If a 30-cm long wrench is used, what is the magnitude of the minimum force required using the wrench? A) 300 N B) 15 N C) 30 N D) 150 N

A) 300 N

The tires of a car support the weight of a stationary car. If one tire has a slow leak, the air pressure within the tire will _______ with time, the surface area between the tire and the road will ________ in time, and the net force the tire exerts on the road will ___________ in time. A) decrease, increase, remain constant B) decrease, increase, decrease C) decrease, decrease, decrease D) increase, increase, increase E) decrease, increase, increase

A) decrease, increase, remain constant

In the figure, determine the character of the collision. The masses of the blocks, and the velocities before and after, are shown. The collision is A) perfectly elastic. B) partially inelastic. C) completely inelastic. D) characterized by an increase in kinetic energy. E) not possible because momentum is not conserved.

A) perfectly elastic.

Three identical oscillators have the same amplitude A and the same angular frequency All three oscillate in simple harmonic motion given by x = A cos The three oscillators have different phase angles however. Rank the three oscillators in order of their displacement x at t = 0, from most positive to most negative. 1. oscillator with Φ=0 2. oscillator with Φ=π/4 3. oscillator with Φ=-π/2 A. 123 B. 231 C. 132 D. 321 E. 312

A. 123

A ball (mass 0.40 kg) is initially moving to the left at 30 m/s. After hitting the wall, the ball is moving to the right at 20 m/s. What is the impulse of the net force on the ball during its collision with the wall? A. 20 kg • m/s to the right B. 20 kg • m/s to the left C. 4.0 kg • m/s to the right D. 4.0 kg • m/s to the left E. none of the above

A. 20 kg • m/s to the right

A Carnot engine takes heat in from a reservoir at 400 K and discards heat to a reservoir at 300 K. If the engine does 12,000 J of work per cycle, how much heat does it take in per cycle? A. 48,000 J B. 24,000 J C. 16,000 J D. 9000 J E. none of the above

A. 48,000 J

A 1400 kg car accelerates uniformly from rest to 60 mph in 6 s. Find the net force needed to produce this motion. 1 mile = 1609.344 m A. 6259 N B. 14000 N C. 1400 N D. 233 N E. 84000 N

A. 6259 N

The kinetic energy KE of an object of mass m moving with speed v is given by the formula K = ½ mv2. The SI unit of kinetic energy is the joule, J. Use this formula to express the joule in terms of the fundamental SI quantities of mass, length, and time. A. J = kg. m2/s2 B. J = kg. m/s2 C. J = kg. m/s D. J = kg. m2. s2

A. J = kg. m2/s2

An ideal gas is taken around the cycle shown in this p-V diagram, from a to b to c and back to a. Process b c is isothermal. For this complete cycle, A. Q> 0, W> 0, deltaU= 0 B. Q < 0, W > 0, deltaU = 0 C. Q = 0, W > 0, deltaU < 0 D. Q = 0, W < 0, deltaU > 0 E. Q > 0, W > 0, deltaU > 0

A. Q> 0, W> 0, deltaU= 0

An ideal gas is taken around the cycle shown in this p-V diagram, from a to b to c and back to a. Process b c is isothermal. For process a b, A. Q> 0, ∆U> 0 B. Q > 0, ∆U = 0 C. Q = 0, ∆U > 0 D. Q = 0, ∆U < 0 E. Q < 0, ∆U < 0

A. Q> 0, ∆U> 0

Increasing the pressure amplitude of a sound wave by a factor of 4 (while leaving the frequency unchanged) A. causes the intensity to increase by a factor of 16. B. causes the intensity to increase by a factor of 4. C. causes the intensity to increase by a factor of 2. D. has no effect on the wave intensity. E. changes the intensity by an amount dependent on the frequency.

A. causes the intensity to increase by a factor of 16.

An incompressible fluid with zero viscosity flows through a pipe of varying radius (shown in cross-section). Compared to the fluid at point P, the fluid at point Q has A. four times the fluid speed. B. twice the fluid speed. C. the same fluid speed. D. half the fluid speed. E. one-quarter the fluid speed.

A. four times the fluid speed.

When a hot cup is filled with cold water, the direction of heat flow is A. from the cup to the water. B. from the water to the cup. C. random, in no particular direction. D. nonexistent.

A. from the cup to the water.

A sample of a low-density gas is initially at room temperature and has pressure p0. The gas is warmed at constant volume until the pressure is 2p0. Compared to the initial Celsius temperature of the gas, the final Celsius temperature is A. greater by a factor of more than 2. B. greater by a factor of 2. C. greater by a factor between 1 and 2. D. the same. E. less.

A. greater by a factor of more than 2.

An ideal gas begins in a thermodynamic state a. When the temperature of the gas is raised from T1 to a higher temperature T2 at a constant volume, a positive amount of heat Q12 flows into the gas. If the same gas begins in state a and has its temperature raised from T1 to T2 at a constant pressure, the amount of heat that flows into the gas is A. greater than Q12. B. equal to Q12. C. less than Q12, but greater than zero. D. zero. E. negative (heat flows out of the system).

A. greater than Q12.

A solid object has a hole in it. Which of these illustrations more correctly shows how the size of the object and the hole change as the temperature increases? A. illustration #1 B. illustration #2 C. The answer depends on the material of which the object is made. D. The answer depends on how much the temperature increases. E. Both C and D are correct.

A. illustration #1

When an ideal gas is allowed to expand isothermally from volume V1 to a larger volume V2, the gas does an amount of work equal to W12. If the same ideal gas is allowed to expand adiabatically from volume V1 to a larger volume V2, the gas does an amount of work that is A. less than W12. B. greater than W12. C. equal to W12. D. either A or B, depending on the ratio of V2 to V1. E. any of A, B, or C, depending on the ratio of V2 to V1.

A. less than W12.

A system can be taken from state a to state balong any of the three paths shown in the p-V diagram. If state b has greater internal energy than state a, along which path is the absolute value |Q| of the heat transfer the greatest? A. path 1 B. path 2 C. path 3 D. |Q| is the same for all three paths. E. Not enough information is given to decide.

A. path 1

When stringing telephone lines between poles in the summer, it is advisable to allow the lines to A. sag. B. be taut. C. be close to the ground. D. allow ample space for birds.

A. sag.

If the specific heat capacity of ice is 0.5 cal/g×C°, how much heat would have to be added to 200 g of ice, initially at a temperature of -10°C, to completely melt the ice? (Latent heat is 80 cal/g) A. 1,000 cal B. 14,000 cal C. 16,000 cal D. 17,000 cal

D. 17,000 cal

You wish to increase the temperature of a 1.00-kg block of a certain solid substance from 20°C to 25°C. (The block remains solid as its temperature increases.) To calculate the amount of heat required to do this, you need to know A. the specific heat of the substance. B. the molar heat capacity of the substance. C. the heat of fusion of the substance. D. the thermal conductivity of the substance. E. more than one of the above.

A. the specific heat of the substance.

This illustration shows the path of a robotic vehicle, or rover. What is the direction of the rover's average acceleration vector for the time interval from t = 0.0 s to t = 2.0 s? A. up and to the left B. up and to the right C. down and to the left D. down and to the right E. none of the above

A. up and to the left

If you toss a ball upward with a certain initial speed, it falls freely and reaches a maximum height h. By what factor must you increase the initial speed of the ball for it to reach a maximum height 3h? A. √3 B. 3 C. 3√3 D. 9 E. 27

A. √3

An ideal gas is taken around the cycle shown in this p-V diagram, from a to b to c and back to a. Process b c is isothermal. Rank the following processes in order of the value of the internal energy ∆U of the ideal gas in the process, from most positive to most negative. A. a b B. b c C. c a

ABC

A pulley has an initial angular speed of 12.5 rad/s and a constant angular acceleration of 3.41 rad/s2. Through what angle does the pulley turn in 5.26 s? A) 160 rad B) 113 rad C) 42.6 rad D) 22.6 rad E) 19.3 rad

B) 113 rad

Sam and George are riding in separate cars on the freeway. The lanes they are driving in are adjacent. We choose our coordinate system so that both are traveling into the positive x-direction. Sam travels at 65 mph and George travels at 72 mph. (a) What is Sam's velocity relative to George? (b) What is George's velocity relative to Sam? A. (a) 7 mph, (b) -7 mph B. (a) -7 mph, (b) 7 mph C. (a) 65 mph, (b) 72mph D. (a) 72 mph, (b) 65mph

B. (a) -7 mph, (b) 7 mph

A Boeing 737 jet plane lands with a speed of 60 m/s (about 135 mi/h) and can decelerate on a wet runway at a maximum rate of 4 m/s2as it comes to rest. What is the minimum time needed before the plane will come to rest? A. 4 s B. 15 s C. 2.25 s D. 12 s E. 35 s

B. 15 s

A girl pulling a sled exerts a 20 N force horizontally for 40 s. How much power does she generate while moving the sled 60 m? A. 20 W B. 30 W C. 40 W D. 120 W

B. 30 W

A ball is fired by a cannon from the top of a cliff as shown in the figure below. Which of the path would the cannonball most closely follow? A. A B. B C. C D. D E. E

B. B

Rank the following temperatures from highest to lowest. A. 20.0°F, B. 20.0°C, C. 20.0 K, D. -80.0°F, E. -80.0°C87 A. ABCED B. BADEC C. CADBE D. EDBCA E. AEBCD

B. BADEC

A copper pot at room temperature is filled with room-temperature water. Imagine a process whereby the water spontaneously freezes and the pot becomes hot. Why is such a process impossible? A. It violates the first law of thermodynamics. B. It violates the second law of thermodynamics. C. It violates both the first and second laws of thermodynamics. D. It violates the law of conservation of energy. E. none of the above

B. It violates the second law of thermodynamics.

A spinning figure skater pulls his arms in as he rotates on the ice. As he pulls his arms in, what happens to his angular momentum L and kinetic energy K? A. L and K both increase. B. L stays the same; K increases. C. L increases; K stays the same. D. L and K both stay the same. E. None of the above.

B. L stays the same; K increases.

An ideal gas is taken around the cycle shown in this p-V diagram, from a to b to c and back to a. Process b c is isothermal. For process b c, A. Q > 0, ∆U > 0 B. Q> 0, ∆U= 0 C. Q = 0, ∆U > 0 D. Q = 0, ∆U < 0 E. Q < 0, ∆U < 0

B. Q> 0, ∆U= 0

You drop a ball from rest and simultaneously shoot a second, identical ball horizontally from the same height as the first ball. If there is no air resistance, which ball hits the ground first? A. The dropped ball hits first. B. The ball shot horizontally hits first. C. They both hit at the same time. D. Answer depends on the speed with which the second ball is shot. E. Answer depends on the speed with which the second ball is shot and the masses of the balls.

B. The ball shot horizontally hits first.

An elevator is being lifted at a constant speed by a steel cable attached to an electric motor. Which statement is correct? A. The cable does positive work on the elevator, and the elevator does positive work on the cable. B. The cable does positive work on the elevator, and the elevator does negative work on the cable. C. The cable does negative work on the elevator, and the elevator does positive work on the cable. D. The cable does negative work on the elevator, and the elevator does negative work on the cable. E. None of the above.

B. The cable does positive work on the elevator, and the elevator does negative work on the cable.

A 10 kg and a 4 kg mass are acted on by the same magnitude net force (which remains constant) for the same period of time. Both masses are at rest before the force is applied. After this time, the 10 kg mass moves with a speed v1and the 4 kg mass moves with a speed v2. Which of the following is true? A. v1is equal to v2. B. The ratio v1/v2is equal to 2/5. C. The ratio v1/v2is equal to 5/2. D. The ratio v1/v2is equal to (2/5)2

B. The ratio v1/v2is equal to 2/5.

When you first step out of a swimming pool on a warm day, you feel cool. This is due primarily to A. conduction. B. convection. C. radiation. D. two of A, B, and C being equally important. E. all three of A, B, and C being equally important.

B. convection.

An elevator is being lifted at a constant speed by a steel cable attached to an electric motor. There is no air resistance, nor is there any friction between the elevator and the walls of the elevator shaft. The upward force exerted on the elevator by the cable is A. greater than the downward force of gravity. B. equal to the force of gravity. C. less than the force of gravity. D. any of the above, depending on the speed of the elevator. E. any of the above, depending on the acceleration of the elevator.

B. equal to the force of gravity.

In an isothermal expansion of an ideal gas, the amount of heat that flows into the gas A. is greater than the amount of work done by the gas. B. equals the amount of work done by the gas. C. is less than the amount of work done by the gas, but greater than zero. D. is zero. E. is negative (heat flows out of the gas).

B. equals the amount of work done by the gas.

The motion diagram shows an object moving along a curved path at constant speed. At which of the points A, C, and E does the object have zero acceleration? A. point A only B. point C only C. point E only D. points A and C only E. points A, C, and E

B. point C only

You are walking on a level floor. You are getting good traction, so the soles of your shoes don't slip on the floor. Which of the following forces should be included in a free-body diagram for your body? A. the force of kinetic friction that the floor exerts on your shoes B. the force of static friction that the floor exerts on your shoes C. the force of kinetic friction that your shoes exert on the floor D. the force of static friction that your shoes exert on the floor E. more than one of these

B. the force of static friction that the floor exerts on your shoes

An ideal gas is taken around the cycle shown in this p-V diagram, from a to b to c and back to a. Process b c is isothermal. Rank the following processes in order of the value of the heat Q into the ideal gas in the process, from most positive to most negative. A. a b B. b c C. c a

BAC

Under standard conditions, the density of air is 1.29 kg/m3. What is the mass of the air inside a room measuring 4.0 m × 3.0 m × 2.0 m? A) 3.1 kg B) 0.32 kg C) 31 kg D) 19 kg E) 1.9 kg

C) 31 kg

A 13,000-N vehicle is to be lifted by a 25-cm diameter hydraulic piston. What force needs to be applied to a 5.0 cm diameter piston to accomplish this? Assume the pistons each have negligible weight. A) 5200 N B) 2600 N C) 520 N D) 260 N

C) 520 N

A block of mass m = 4.4 kg, moving on frictionless surface with a speed vi = 9.2 m/s makes a sudden perfectly elastic collision with a second block of mass M, as shown in the figure. The second block is originally at rest. Just after the collision, the 4.4-kg block recoils with a speed of vf = 2.5 m/s. What is the mass M of the second block? A) 12 kg B) 4.4 kg C) 7.7 kg D) 21 kg E) 5.6 kg

C) 7.7 kg

This is the x-t graph for an object moving along the x-axis. Which of the following descriptions of the motion is most accurate? A. (velocity at C) > (velocity at B) > (velocity at A) B. (velocity at A) > (velocity at B) > (velocity at C) C. (velocity at A) > (velocity at C) > (velocity at B) D. (velocity at C) > (velocity at A) > (velocity at B) E. (velocity at C) = (velocity at A) > (velocity at B)

C. (velocity at A) > (velocity at C) > (velocity at B)

When you apply an upward force of magnitude F to a block of mass 2.00 kg, the block accelerates upward at 3.00 m/s2. You can ignore any forces exerted on the block by the air. Rank the following forces in order of their magnitude, from largest to smallest. 1) force F 2) the net force on the block 3) the gravitational force on the block A. 123 B. 231 C. 132 D. 321

C. 132

During one cycle, an automobile engine with an efficiency of 20% takes in 10,000 J of heat. How much work does the engine do per cycle? A. 8000 J B. 6400 J C. 2000 J D. 1600 J E. 400 J

C. 2000 J

A 1200 kg car's speed changes from 0 to 20 m/s in 4 s. What is the average power of the car motor during this time period? Neglect friction. A. 1200 W B. 24 kW C. 60 kW D. 3 kW

C. 60 kW

The two ramps shown are both frictionless. The heights y1and y2are the same for each ramp. A block of mass m is released from rest at the left-hand end of each ramp. Which block arrives at the right-hand end with the greater speed? A. The block on the curved track arrives with greater speed. B. The block on the straight track arrives with greater speed. C. Both blocks arrive at the right-hand end with the same speed. D. The answer depends on the shape of the curved track.

C. Both blocks arrive at the right-hand end with the same speed.

A ball is thrown vertically upward, and as it comes down; it is caught at its initial position. Which of the following graphs best represents the velocity of the ball as a function of time? A. A B. B C. C D. D

C. C

In which of these situations would the average velocity vector over an interval be equal to the instantaneous velocity at the end of the interval? A. a body moving along a curved path at constant speed B. a body moving along a curved path and speeding up C. a body moving along a straight line at constant speed D. a body moving along a straight line and speeding up E. more than one of these

C. a body moving along a straight line at constant speed

If the pressure of the atmosphere is below the triple-point pressure of a certain substance, that substance can exist (depending on the temperature) A. as a liquid or as a vapor, but not as a solid. B. as a liquid or as a solid, but not as a vapor. C. as a solid or as a vapor, but not as a liquid. D. as a solid, a liquid, or a vapor. E. Not enough information is given to decide.

C. as a solid or as a vapor, but not as a liquid.

This p-V diagram shows two ways to take a system from state a (at lower left) to state c (at upper right):• via state b (at upper left), or• via state d (at lower right)For which path is W > 0? A. path abc only B. path adc only C. both path abc and path adc D. neither path abc nor path adc E. The answer depends on what the system is made of.

C. both path abc and path adc

A lightweight crate (A) and a heavy crate (B) are side-by-side on a horizontal floor. You apply a horizontal force F to crate A. There is friction between the crates and the floor. If the two crates are accelerating to the right, A. crate A exerts more force on crate B than B exerts on A. B. crate A exerts less force on crate B than B exerts on A. C. crate A exerts as much force on crate B as B exerts on A. D. answer depends on the details of the friction force. E. answer depends on the magnitude of the acceleration.

C. crate A exerts as much force on crate B as B exerts on A.

You toss a 0.150-kg baseball straight upward so that it leaves your hand moving at 20.0 m/s. The ball reaches a maximum height y2. What is the speed of the ball when it is at a height of y2/2? Ignore air resistance. A. 10.0 m/s B. less than 10.0 m/s but greater than zero C. greater than 10.0 m/s D. zero E. Not enough information is given to decide.

C. greater than 10.0 m/s

You toss a ball straight upward, in the positive direction. The ball falls freely under the influence of gravity. At the highest point in the ball's motion, A. its velocity is zero and its acceleration is zero. B. its velocity is zero and its acceleration is positive (upward). C. its velocity is zero and its acceleration is negative (downward). D. its velocity is positive (upward) and its acceleration is zero. E. its velocity is negative (downward) and its acceleration is zero.

C. its velocity is zero and its acceleration is negative (downward).

A cable attached to a car holds the car at rest on the frictionless ramp (angle ⍺= 900). The ramp exerts a normal force on the car. How does the magnitude n of the normal force compare to the weight w of the car? A. n = w B. n > w C. n< w D. Two of these are possible, depending on the value of ⍺. E. All three of these are possible, depending on the value of ⍺.

C. n< w

The velocity and acceleration of an object at a certain instant areAt this instant, the object is A. speeding up and following a curved path. B. speeding up and moving in a straight line. C. slowing down and following a curved path. D. slowing down and moving in a straight line. E. none of these.

C. slowing down and following a curved path.

The force on a damped oscillator is Fx= -kx - bvx. During its motion, the oscillator loses mechanical energy most rapidly A. when it is at maximum positive displacement. B. when it is at maximum negative displacement. C. when it is passing through the equilibrium position. D. when it is at either maximum positive or maximum negative displacement. E. Misleading question—the oscillator loses mechanical energy at the same rate at all times during the motion.

C. when it is passing through the equilibrium position.

If a cyclist is going around a curve at constant speed, is he accelerating? If so, what is the direction of his acceleration? A.No, he is not accelerating. B.Yes, he is accelerating in the direction of his motion. C.Yes, he is accelerating toward the inside of the curve. D.Yes, he is accelerating toward the outside of the curve. E.Yes, he is accelerating in some other direction.

C.Yes, he is accelerating toward the inside of the curve.

Rank the following heat engines in order from highest to lowest thermal efficiency. A. An engine that in one cycle absorbs 2500 J of heat and rejects 2250 J of heat B. An engine that in one cycle absorbs 50,000 J of heat and does 4000 J of work C. An engine that in one cycle does 800 J of work and rejects 5600 J of heat

CAB

A golf club exerts an average horizontal force of 1000 N on a 0.045-kg golf ball that is initially at rest on the tee. The club is in contact with the ball for 1.8 ms. What is the speed of the golf ball just as it leaves the tee? A) 30 m/s B) 35 m/s C) 50 m/s D) 40 m/s E) 45 m/s

D) 40 m/s

A pump uses a piston of 15 cm diameter that moves at 2.0 cm/s as it pushes a fluid through a pipe. What is the speed of the fluid when it enters a portion of the pipe that is 3.0 mm in diameter? Treat the fluid as ideal and incompressible. A) 50 cm/s B) 6.0 cm/s C) 22 cm/s D) 50 m/s

D) 50 m/s

A sled travels over the crest of a snow-covered hill. The sled slows down as it climbs up the left-hand side of the hill and gains speed as it descends on the right-hand side. Which of the vectors in the figure correctly shows the direction of the sled's acceleration at the crest? A. #1 (to the left) B. #2 (straight up) C. #3 (to the right) D. #4 (straight down) E. none of these

D. #4 (straight down)

When the temperature of a certain solid, rectangular object increases by ∆T, the length of one side of the object increases by 0.010% = 1.0 10-4 of the original length. The increase in volumeof the object due to this temperature increase is A. 0.010% = 1.0 10-4 of the original volume. B. (0.010)3% = 0.0000010% = 1.0 10-8 of the original volume. C. (1.0 10-4)3 = 0.00000000010% = 1.0 10-12 of the original volume. D. 0.030% = 3.0 10-4 of the original volume. E. Not enough information is given to decide.

D. 0.030% = 3.0 10-4 of the original volume.

A block of ice (density 920 kg/m3), a block of concrete (density 2000 kg/m3), and a block of iron (density 7800 kg/m3) are all submerged in the same fluid. All three blocks have the same volume. Which block experiences the greatest buoyant force? A. The block of ice experiences the greatest buoyant force. B. The block of concrete experiences the greatest buoyant force. C. The block of iron experiences the greatest buoyant force. D. All three experience the same buoyant force. E. The answer depends on the density of the fluid.

D. All three experience the same buoyant force.

You put an ice cube at 0°C inside a large metal box at 70°C. The ice melts and the entropy of the ice increases. Which statement is correct? A. Entropy of the metal box is unchanged; total entropy increases. B. Entropy of the metal box decreases; total entropy decreases. C. Entropy of the metal box decreases; total entropy is unchanged. D. Entropy of the metal box decreases; total entropy increases. E. none of the above

D. Entropy of the metal box decreases; total entropy increases.

A car's speed changes from 20 mph to 60 mph. By what factor does its kinetic energy change? A. There is no way to tell. B. It will increase by a factor of 3. C. It will increase by a factor of 6. D. It will increase by a factor of 9. E. It will stay constant.

D. It will increase by a factor of 9.

An ideal gas is taken around the cycle shown in this p-V diagram, from a to c to b and back to a. Process c b is adiabatic. For process c b, A. Q > 0, W > 0, ∆U = 0 B. Q > 0, W > 0, ∆U > 0 C. Q = 0, W > 0, ∆U < 0 D. Q= 0, W< 0, ∆U> 0 E. Q < 0, W < 0, ∆U = 0

D. Q= 0, W< 0, ∆U> 0

A rock is thrown straight up from the surface of the Earth. Which one of the following statements describes the energy transformation of the rock as it rises? Neglect air resistance. A. The total energy of the rock increases. B. The KE increases and the PE decreases. C. Both the PE and the total energy of the rock increase. D. The KE decreases and the PE increases.

D. The KE decreases and the PE increases.

On a humid summer day, perspiration does not cool you off much. Why? A. The air density is extremely low and the air pressure is too high to permit water to evaporate. B. The water vapor in the air is moving too fast to condense on your skin as perspiration. C. The air density is extremely low and its pressure is too low to permit water to evaporate. D. The air is almost saturated with water vapor and there is almost no net evaporation.

D. The air is almost saturated with water vapor and there is almost no net evaporation.

A chair has a wooden seat but metal legs. The chair legs feel colder to the touch than does the seat. Why is this? A. The metal is at a lower temperature than the wood. B. The metal has a higher specific heat than the wood. C. The metal has a lower specific heat than the wood. D. The metal has a higher thermal conductivity than the wood.

D. The metal has a higher thermal conductivity than the wood.

An incompressible fluid with zero viscosity flows through a pipe of varying radius (shown in cross-section). Compared to the fluid at point P, the fluid at point Q has A. a greater pressure and a greater volume flow rate. B. a greater pressure and the same volume flow rate. C. the same pressure and a greater volume flow rate. D. a lower pressure and the same volume flow rate. E. none of the above.

D. a lower pressure and the same volume flow rate.

A projectile is launched at a 30° angle above the horizontal. Ignore air resistance. The projectile's acceleration is greatest A. at a point between the launch point and the high point of the trajectory. B. at the high point of the trajectory. C. at a point between the high point of the trajectory and where it hits the ground. D. misleading question—the acceleration is the same (but nonzero) at all points along the trajectory E. misleading question—the acceleration is zero at all points along the trajectory

D. misleading question—the acceleration is the same (but nonzero) at all points along the trajectory

The sphere on the right has twice the mass and twice the radius of the sphere on the left. Compared to the sphere on the left, the larger sphere on the right has A. twice the density. B. the same density. C. half the density. D. one-quarter the density. E. one-eighth the density.

D. one-quarter the density.

A pitcher contains 0.50 kg of liquid water at 0°C and 0.50 kg of ice at 0°C. You let heat flow into the pitcher until there is 0.75 kg of liquid water and 0.25 kg of ice. During this process, the temperature of the ice-water mixture A. increases slightly. B. decreases slightly. C. first increases slightly, then decreases slightly. D. remains the same. E. The answer depends on the rate at which heat flows.

D. remains the same

A simple pendulum consists of a point mass suspended by a massless, unstretchable string. If the mass is doubled while the length of the string remains the same, the period of the pendulum A. becomes four times greater. B. becomes twice as great. C. becomes greater by a factor of √2 D. remains unchanged. E. decreases.

D. remains unchanged.

This is an x-t graph for an object in simple harmonic motion. At which of the following times does the object have the most negative acceleration ax? A. t = T/4 B. t = T/2 C. t = 3T/4 D. t= T E. Two of the above are tied for most negative acceleration.

D. t= T

When you sit facing a campfire outdoors, your face feels quite warm because A. microwaves from the moving charged particles heat your skin. B. convection from the fire is carrying hot air sideways to your face. C. conduction in the air is carrying heat from the flames to your skin. D. the campfire is radiating heat towards your skin.

D. the campfire is radiating heat towards your skin.

At a compression in a sound wave, A. particles are displaced by the maximum distance in the same direction as the wave is moving. B. particles are displaced by the maximum distance in the direction opposite to the direction the wave is moving. C. particles are displaced by the maximum distance in the direction perpendicular to the direction the wave is moving. D. the particle displacement is zero. E. more than one of the above can be true, depending on circumstances.

D. the particle displacement is zero.

Two blocks are connected as shown. When released, the 6.00-kg block accelerates downward, and the 8.00-kg block accelerates to the right. After each block has moved 2.00 cm, the force of gravity has done A. work on both blocks, but more work on the 8.00-kg block than on the 6.00-kg block. B. the same amount of work on both blocks. C. work on both blocks, but less work on the 8.00-kg block than on the 6.00-kg block. D. work on the 6.00-kg block only. E. Not enough information is given to decide.

D. work on the 6.00-kg block only.

Three blocks are connected as shown. The ropes and pulleys are of negligible mass. When released, block C moves downward, block B moves up the ramp, and block A moves to the right. After each block has moved a distance d, the force of gravity has done A. positive work on A, B, and C. B. positive work on A and B, and negative work on C. C. zero work on A, positive work on B, and negative work on C. D. zero work on A, negative work on B, and positive work on C. E. none of these.

D. zero work on A, negative work on B, and positive work on C.

A 15-kg child is sitting on a playground teeter-totter, 1.5 m from the pivot. What is the magnitude of the minimum force, applied 0.30 m on the other side of the pivot, that is needed to make the child lift off the ground? A) 23 N B) 44 N C) 75 N D) 66 N E) 740 N

E) 740 N

During one cycle, an automobile engine takes in 12,000 J of heat and discards 9000 J of heat. What is the efficiency of this engine? A. 400% B. 133% C. 75% D. 33% E. 25%

E. 25%

If you increase the temperature of a given amount of an ideal gas, what happens to the gas pressure p and the volume V of the gas? A. p increases. B. V increases. C. p and V both increase. D. Either p increases and V decreases, or p decreases and V increases. E. Not enough information is given to decide.

E. Not enough information is given to decide.

An ideal gas is taken around the cycle shown in this p-V diagram, from a to b to c and back to a. Process b c is isothermal. For process c a, A. Q > 0, ∆U > 0 B. Q > 0, ∆U = 0 C. Q = 0, ∆U > 0 D. Q = 0, ∆U < 0 E. Q< 0, ∆U< 0

E. Q< 0, ∆U< 0

The illustration shows a thermometer that uses a column of liquid (usually mercury or ethanol) to measure air temperature. In thermal equilibrium, this thermometer measures the temperature of A. the column of liquid. B. the glass that encloses the liquid. C. the air outside the thermometer. D. both A and B. E. all of A, B, and C.

E. all of A, B, and C.

A system can be taken from state a to state balong any of the three paths shown in the p-V diagram. If state b has greater internal energy than state a, along which path is there a net flow of heat out of the system? A. path 1 B. path 2 C. path 3 D. all of paths 1, 2, and 3 E. none of paths 1, 2, or 3

E. none of paths 1, 2, or 3

A bicyclist starts at point P and travels around a triangular path that takes her through points Q and Rbefore returning to point P. What is the magnitude of her net displacement for the entire round trip?A. 100 m B. 200 m C. 600 m D. 1200 m E. zero

E. zero

You immerse a 1-kg block of iron in 1 kg of water in an insulated chamber, add 100 J of heat, and allow the iron and water to equilibrate to the same temperature. Which has absorbed more heat, the iron or the water? a. They absorb the same amount of heat. b. The iron absorbs more heat. c. The water absorbs more heat.

c. The water absorbs more heat.