Physics 1, Module 3

E

44) A car moving at 50 km/hr skids 20 m with locked brakes. How far will the car skid with locked brakes if it is traveling at 150 km/hr? A) 20 m B) 60 m C) 90 m D) 120 m E) 180 m

C

6) A rifle recoils from firing a bullet. The speed of the rifle's recoil is small because the A) force against the rifle is smaller than against the bullet. B) momentum is mainly concentrated in the bullet. C) rifle has much more mass than the bullet. D) momentum of the rifle is smaller.

C

6) If you do work on an object in half the usual time, your power output is A) half the usual power output. B) the usual power output. C) twice the usual power output.

C

8) Do 100 J of work in 50 s and your power output is A) 1/4 W. B) 1/2 W. C) 2 W. D) 4 W. E) more than 4 W.

C

10) In order to catch a ball, a baseball player extends the hand forward before impact with the ball and then lets it ride backward in the direction of the ball's motion upon impact. Doing this reduces the force of impact on the player's hand principally because the A) force of impact is reduced. B) relative velocity is less. C) time of impact is increased. D) time of impact is decreased. E) none of these.

C

10) When an object is lifted 10 meters, it gains a certain amount of potential energy. If the same object is lifted 20 meters, its potential energy gain is A) less. B) the same. C) twice as much. D) four times as much. E) more than 4 times as much.

A

20) Recoil is noticeable if we throw a heavy ball while standing on roller skates. If instead we go through the motions of throwing the ball but hold onto it, our net recoil will be A) zero. B) the same as before. C) small, but noticeable.

A

21) A heavy truck and a small car rolling down a hill at the same speed are forced to stop in the same amount of time. Compared to the force that stops the car, the force needed to stop the truck is A) greater. B) smaller. C) the same.

E

22) A 1-N apple falls to the ground. The apple hits the ground with an impact force of about A) 1 N. B) 2 N. C) 4 N. D) 9.8 N. E) not enough information given to say.

D

23) A karate expert executes a swift blow and severs a cement block with her bare hand. The magnitude is the same for the A) impulse on both the block and the expert's hand B) force on both the block and the expert's hand. C) time of impact on both the block and the expert's hand. D) all of these. E) none of these.

A

7) Exert 1 N for a distance of 1 m in 1 s and you deliver a power of A) 1 W. B) 2 W. C) 1/3 W. D) 3 W. E) none of these.

A

7) Suppose a gun were made of a strong but very light material. Suppose also that the bullet is more massive than the gun itself. For such a weapon A) the target would be safer than the shooter. B) recoil problems would be lessened. C) conservation of energy would not hold. D) conservation of momentum would not hold. E) both conservation of energy and momentum would not hold.

A

A marble is rolling back and forth along the path shown. Figure 7-A 20) At position A, is the marble's kinetic energy less than, greater than, or the same as its kinetic energy when it is at B? A) less B) greater C) the same

C

50) A jack system will increase the potential energy of a heavy load by no more than 1000 J with a work input of 2000 J. The efficiency of the jack system is no more than A) 10%. B) 20%. C) 50%. D) 80%. E) not enough information given.

E

50) A sandbag is motionless in outer space. A second sandbag with 3 times the mass moving at 12 m/s collides with it. They stick together and move at a speed of A) 3 m/s. B) 4 m/s. C) 6 m/s. D) 8 m/s. E) none of these

A

1) If you push for an hour against a stationary wall, you do no work A) on the wall. B) at all. C) both of these D) none of these

B

1) Which of the following has the largest momentum relative to the Earth? A) a tightrope walker crossing Niagara Falls B) a pickup truck speeding along a highway C) a Mack truck parked in a parking lot D) the Science building on campus E) a dog running down the street

C

11) A 1000-kg car and a 2000-kg car are hoisted the same distance in a gas station. Raising the more massive car requires A) less work. B) as much work. C) twice as much work. D) four times as much work. E) more than 4 times as much work.

C

11) When you jump from an elevated position you usually bend your knees upon reaching the ground. By doing this, you make the time of the impact about 10 times as great as for a stiff-legged landing. In this way the average force your body experiences is A) less than 1/10 as great. B) more than 1/10 as great. C) about 1/10 as great. D) about 10 times as great.

A

12) An object that has kinetic energy must be A) moving. B) falling. C) at an elevated position. D) at rest. E) none of these.

A

12) When you are in the way of a fast-moving object and can't get out of its way, you will suffer a smaller force of impact if you decrease its momentum over a A) long time. B) short time. C) same way either way.

E

13) A car traveling along the highway needs a certain amount of force exerted on it to stop it in a certain distance. More stopping force is required when the car has A) more mass. B) more momentum. C) less stopping distance. D) all of these. E) none of these.

D

13) An object that has potential energy may have this energy because of its A) speed. B) acceleration. C) momentum. D) location. E) none of these.

D

14) A bullet is fired from a gun. The speed of the bullet will be about the same as the speed of the recoiling gun A) because momentum is conserved. B) because velocity is conserved. C) because both velocity and momentum are conserved. D) if the mass of the bullet equals the mass of the gun. E) none of these.

A

14) Bullets are fired from an airplane in the forward direction of motion. The momentum of the airplane will be A) decreased. B) unchanged. C) increased.

A

15) A clerk can lift containers a vertical distance of 1 meter or can roll them up a 2 meter-long ramp to the same elevation. With the ramp, the applied force required is about A) half as much. B) twice as much. C) the same.

E

15) Padded dashboards in cars are safer in an accident than nonpadded ones because an occupant hitting the dash has A) increased time of impact. B) decreased impulse. C) decreased impact force. D) a and b above. E) a and c above.

C

16) A bow is drawn so that it has 40 J of potential energy. When fired, the arrow will ideally have a kinetic energy of A) less than 40 J. B) more than 40 J. C) 40 J.

D

16) The force on an apple hitting the ground depends upon A) the speed of the apple just before it hits. B) the time of impact with the ground. C) whether or not the apple bounces. D) all of these.

B

17) Compared to falling on a wooden floor, a wine glass may not break when it falls to a carpeted floor because of the A) lesser impulse in stopping. B) longer time to stop. C) both of these. D) neither of these.

E

17) When a car is braked to a stop, its kinetic energy is transformed to A) stopping energy. B) potential energy. C) energy of motion. D) energy of rest. E) heat.

A

18) A 4 kg ball has a momentum of 12 kg m/s. What is the ball's speed? A) 3 m/s B) 4 m/s C) 12 m/s D) 48 m/s E) none of these

B

18) A hydraulic press, like a simple lever, properly arranged is capable of multiplying energy input. A) sometimes true B) always false C) always true

B

19) A ball is moving at 4 m/s and has a momentum of 48 kg m/s. What is the ball's mass? A) 4 kg B) 12 kg C) 48 kg D) 192 kg E) none of these

A

19) A hydraulic press, like a simple lever, properly arranged is capable of multiplying force input. A) true B) false

A

2) If you push an object twice as far while applying the same force you do A) twice as much work. B) four times as much work. C) the same amount of work.

B

2) The difference between impulse and impact force involves the A) distance the force acts. B) time the force acts. C) difference between acceleration and velocity. D) mass and its effect on resisting a change in momentum.

C

24) A piece of putty moving with 1 unit of momentum strikes and sticks to a heavy bowling ball that is initially at rest. After the putty sticks to the ball, both move with a combined momentum of A) less than 1 unit. B) more than 1 unit. C) 1 unit. D) not enough information.

B

25) A 1-kg chunk of putty moving at 1 m/s collides with and sticks to a 5-kg bowling ball initially at rest. The bowling ball and putty then move with a momentum of A) 0 kg m/s. B) 1 kg m/s. C) 2 kg m/s. D) 5 kg m/s. E) more than 5 kg m/s.

D

26) The force that accelerates a rocket in outer space is exerted on the rocket by the A) rocket's engine. B) rocket's wings. C) atmospheric pressure. D) exhaust gases. E) none of these.

C

27) No work is done by gravity on a bowling ball that rolls along a bowling alley because A) no force acts on the ball. B) no distance is covered by the ball. C) the force on the ball is at right angles to the ball's motion. D) no potential energy is being converted to kinetic energy. E) its kinetic energy remains constant.

A

27) Two billiard balls having the same mass roll toward each other, each moving at the same speed. What is the combined momentum of the two balls? A) 0 kg m/s. B) 10 kg m/s. C) more information need to determine.

C

28) Compared to the force that brings a small car to a stop, the force required to bring a heavy truck traveling at the same speed to a stop A) is less. B) is more. C) may be less and may be more.

C

28) Which requires more work: lifting a 50-kg sack vertically 2 meters or lifting a 25-kg sack vertically 4 meters? A) lifting the 50-kg sack B) lifting the 25-kg sack C) Both require the same amount of work.

C

29) A 50-kg sack is lifted 2 meters in the same time as a 25-kg sack is lifted 4 meters. The power expended in raising the 50-kg sack compared to the power used to lift the 25-kg sack is A) twice as much. B) half as much. C) the same.

B

29) A cannonball shot from a cannon with a long barrel will have a greater muzzle velocity because the cannonball receives a greater A) force. B) impulse. C) both of these. D) neither of these.

A

3) If you push an object just as far while applying twice the force you do A) twice as much work. B) four times as much work. C) the same amount of work.

B

3) It is correct to say that impulse is equal to A) momentum. B) the change in momentum. C) the force multiplied by the distance the force acts. D) all of these. E) none of these.

D

30) A TV set is pushed a distance of 2 m with a force of 20 N that is in the same direction as the set moves. How much work is done on the set? A) 2 J B) 10 J C) 20 J D) 40 J E) 80 J

C

30) According to the impulse-momentum equation Ft = change in (mv), a person will suffer less injury falling on a wooden floor which "gives" than on a more rigid cement floor. The "F" in the above equation stands for the force exerted on the A) person. B) floor. C) both of these. D) none of these.

B

31) A 1000-kg car moving at 10 m/s brakes to a stop in 5 s. The average braking force is A) 1000 N. B) 2000 N. C) 3000 N. D) 4000 N. E) 5000 N.

B

31) It takes 40 J to push a large box 4 m across a floor. Assuming the push is in the same direction as the move, what is the magnitude of the force on the box? A) 4 N B) 10 N C) 40 N D) 160 N E) none of these

D

32) A 2-kg mass is held 4 m above the ground. What is the approximate potential energy of the mass with respect to the ground? A) 20 J B) 40 J C) 60 J D) 80 J E) none of these.

C

32) Which would be more damaging, driving into a very massive concrete wall with no "give," or having a head-on collision at the same speed with an identical car moving toward you with the same speed? It would be more damaging to hit the A) car. B) wall. C) both the same.

B

33) A 2-kg mass has 40 J of potential energy with respect to the ground. Approximately how far is it located above the ground? A) 1 m B) 2 m C) 3 m D) 4 m E) none of these

D

33) A rifle of mass 2 kg is suspended by strings. The rifle fires a bullet of mass 1/100 kg at a speed of 200 m/s. The recoil velocity of the rifle is about A) 0.001 m/s. B) 0.01 m/s. C) 0.1 m/s. D) 1 m/s. E) none of these.

C

34) A 5-kg fish swimming at a speed of 1 m/s swallows an absent-minded 1-kg fish at rest. The speed of the larger fish after lunch is A) 1/2 m/s. B) 2/5 m/s. C) 5/6 m/s. D) 6/5 m/s. E) 1 m/s.

D

34) A heavy pile driver starting from rest falls on a pile with a force that depends on A) the original height of the driver. B) the original potential energy of the driver. C) the distance the pile is moved. D) all of these. E) none of these.

C

35) A 5-kg fish swimming at a speed of 1 m/s swallows an absent-minded 1-kg fish swimming toward it at 4 m/s. The speed of the larger fish after lunch is A) 1/2 m/s. B) 1/5 m/s. C) 1/6 m/s. D) 2/3 m/s. E) 3/2 m/s.

B

35) Using 1000 J of work, a toy elevator is raised from the ground floor to the second floor in 20 seconds. How much power does the elevator use? A) 20 W B) 50 W C) 100 W D) 1000 W E) 20,000 W

C

36) A 1-kg chunk of putty moving at 1 m/s collides with and sticks to a 5-kg bowling ball that is initially at rest. The bowling ball and putty are then in motion with a speed of A) 1/4 m/s. B) 1/5 m/s. C) 1/6 m/s. D) none of these. E) not enough information given.

B

36) One end of a long, uniform log is raised to shoulder level. Another identical log is raised at its center to the same level. Raising the second log requires about A) the same amount of work. B) twice as much work. C) more than twice as much work.

B

37) Momentum is transferred to the ground when an apple falls on it. The momentum absorbed by the ground is A) negligible compared to the momentum of the apple. B) greater than that of the apple only if the apple bounces. C) greater than that of the apple in all cases. D) none of these.

B

37) Two identical arrows, one with twice the kinetic energy of the other, are fired into a hay bale. The faster arrow will penetrate A) the same distance as the slower arrow. B) twice as far as the slower arrow. C) four times as far as the slower arrow. D) more than four times as far as the slower arrow. E) none of these.

D

38) A car moves 4 times as fast as another identical car. Compared to the slower car, the faster car has A) 4 times the KE. B) 8 times the KE. C) 12 times the KE. D) 16 times the KE.

A

38) A fan attached to an ice sailcraft stalled on a windless day blows air into the sail that bounces backward upon impact. The boat can A) then move in the direction of the wind impact force. B) not move by this wind impact. C) then move, but in the opposite direction of the wind impact force.

A

39) A ball is projected into the air with 100 J of kinetic energy which is transformed to gravitational potential energy at the top of its trajectory. When it returns to its original level after encountering air resistance, its kinetic energy is A) less than 100 J. B) more than 100 J. C) 100 J. D) not enough information given.

B

39) If all people, animals, trains and trucks all over the world began to walk or run towards the east, then the A) earth would spin a bit faster. B) earth would spin a bit slower. C) earth's spin would not be affected at all.

C

4) If you push an object with twice the work input for twice the time, your power input is A) twice. B) four times as much. C) the same amount as for half the work in half the time.

B

4) The impulse-momentum relationship is a direct result of A) Newton's 1st law. B) Newton's 2nd law. C) Newton's 3rd law.

D

40) Strictly speaking, if any electrical device in your car is turned on (such as an air conditioner, headlights, or even a radio) more gasoline is burned by the engine. This statement is A) totally false. B) true only if the car's engine is running. C) true only if the car's engine is stopped. D) almost always true. E) none of these.

C

40) You're driving down the highway and a bug spatters into your windshield. Which undergoes the greater change in momentum? A) the bug B) your car C) both the same

A

41) A machine puts out 100 Watts of power for every 1000 Watts put into it. The efficiency of the machine is A) 10%. B) 50%. C) 90%. D) 110%. E) none of these.

B

41) If the ball is as massive as the astronaut, the A) astronaut will catch one bounce only. B) astronaut will never catch the first bounce. C) astronaut's time between catches will decrease as the game progresses. D) none of these.

B

42) An ungloved fist will do more damage to a jaw than a gloved fist. The reason for this is that the ungloved fist A) delivers a larger impulse to the jaw. B) exerts a larger force on the jaw. C) has less air resistance on it. D) none of these.

C

42) If the ball is as massive as the astronaut, the distance between the moving ball and the moving astronaut after the first bounce A) increases with time. B) decreases with time. C) remains constant with time.

A

43) A woman lifts a box from the floor. She then moves with constant speed to the other side of the room, where she puts the box down. How much work does she do on the box while walking across the floor at constant speed? A) zero J B) more than zero J C) more information needed to determine

A

43) If the ball is one hundredth as massive as the astronaut, the time between catches A) increases as the game progresses. B) stays the same as the game progresses. C) decreases as the game progresses.

B

44) A golf ball moving forward with 1 unit of momentum strikes and bounces backward off a heavy bowling ball that is initially at rest and free to move. The bowling ball is set in motion with a momentum of A) less than 1 unit. B) more than 1 unit. C) 1 unit. D) not enough information.

C

45) Consider massive gliders that slide friction-free along a horizontal air track. Glider A has a mass of 1 kg, a speed of 1 m/s, and collides with Glider B that has a mass of 5 kg and is at rest. If they stick upon collision, their speed after collision will be A) 1/4 m/s. B) 1/5 m/s. C) 1/6 m/s. D) 1 m/s. E) none of these.

B

45) Which has greater kinetic energy, a car traveling at 30 km/hr or a car of half the mass traveling at 60 km/hr? A) the 30 km/hr car B) the 60 km/hr car C) Both have the same kinetic energy.

C

46) A 1-kg glider and a 2-kg glider both slide toward each other at 1 m/s on an air track. They collide and stick. The combined mass moves at A) 0 m/s. B) 1/2 m/s. C) 1/3 m/s. D) 1/6 m/s. E) 1.5 m/s.

D

46) A diver who weighs 500 N steps off a diving board that is 10 m above the water. The diver hits the water with kinetic energy of A) 10 J. B) 500 J. C) 510 J. D) 5000 J. E) more than 5000 J.

C

47) Consider a hydraulic press. When the input piston is depressed 20 cm, the output piston is observed to move 1 cm. On the same press, an input force of 1 N can raise no more than A) 1 N. B) 10 N. C) 20 N. D) 21 N.

A

47) Two identical gliders slide toward each other on an air track. One moves at 1 m/s and the other at 2 m/s. They collide and stick. The combined mass moves at A) 1/2 m/s. B) 1/3 m/s. C) 1/6 m/s. D) 3/4 m/s. E) 1.5 m/s.

C

48) A 2500-N pile-driver ram falls 10 m and drives a post 0.1 m into the ground. The average impact force on the ram is A) 2,500 N. B) 25,000 N. C) 250,000 N. D) 2,500,000 N.

C

48) A 5000-kg freight car runs into a 10,000-kg freight car at rest. They couple upon collision and move with a speed of 2 m/s. What was the initial speed of the 5000-kg car? A) 4 m/s B) 5 m/s C) 6 m/s D) 8 m/s E) none of these

C

49) A 5000-kg freight car moving at 2 m/s runs into a 10,000-kg freight car at rest. They couple upon collision and move away as one body at A) 2 m/s. B) 1 m/s. C) 2/3 m/s. D) 1/3 m/s.

E

49) A pulley system raises a 1000-N load with 100 N of input force. The efficiency of the system is A) 10%. B) 90%. C) 100%. D) 1000%. E) not enough information given.

B

5) A job is done slowly, while an identical job is done quickly. Both jobs require the same amount of work, but different amounts of A) energy. B) power. C) both of these. D) none of these.

C

5) The conservation of momentum is most closely related to A) Newton's 1st law. B) Newton's 2nd law. C) Newton's 3rd law.

C

8) Two objects, A and B, have the same size and shape, but A is twice as heavy as B. When they are dropped simultaneously from a tower, they reach the ground at the same time, but A has a greater A) speed. B) acceleration. C) momentum. D) all of these. E) none of these.

C

9) A heavy truck and a small truck roll down a hill. Neglecting friction, at the bottom of the hill, the heavy truck will have greater A) speed. B) acceleration. C) momentum. D) all of these. E) none of these.

B

9) When an object is raised above the ground it gains a certain amount of potential energy. If the same object is raised twice as high it gains A) four times as much potential energy. B) twice as much potential energy. C) neither of these.

A

A small ball tied to a string swings without air resistance, beginning from rest at point A. The string snags on a nail at point P, causing the ball to move in a small circle.Figure 7-B 21) The ball has maximum potential energy at point A) A. B) B. C) C. D) D. E) E.

B

A small ball tied to a string swings without air resistance, beginning from rest at point A. The string snags on a nail at point P, causing the ball to move in a small circle.Figure 7-B 22) The ball has maximum kinetic energy at point A) A. B) B. C) C. D) D. E) E.

B

A small ball tied to a string swings without air resistance, beginning from rest at point A. The string snags on a nail at point P, causing the ball to move in a small circle.Figure 7-B 23) The ball has maximum speed at point A) A. B) B. C) C. D) D. E) E.

E

A small bead slides without friction along the wire shown here, beginning at point A. The wire does not touch itself at point C, so the bead has room to slide past that point. 24) The bead has maximum kinetic energy at point A) A. B) B. C) C. D) D. E) F.

A

A small bead slides without friction along the wire shown here, beginning at point A. The wire does not touch itself at point C, so the bead has room to slide past that point. 25) The bead has maximum potential energy at point A) A. B) B. C) C. D) D. E) F.

E

A small bead slides without friction along the wire shown here, beginning at point A. The wire does not touch itself at point C, so the bead has room to slide past that point. 26) The bead has maximum speed at point A) A. B) B. C) C. D) D. E) F.