Quiz 4-1Your response has been submitted successfully.

Points Awarded  13

Points Missed  0

Percentage  100%

1. Which of the following undergoes the greatest change in momentum?

A. A baseball that is caught. B. A baseball that is thrown. C. A baseball that is caught and thrown back with the same speed. D. They all have the same impulse.

Points Earned: 1/1

Correct Answer: C

Your Response: C

2. A force is applied to stop a moving shopping cart. Increasing the time interval over which the force is applied

A. requires a greater force. B. has no effect on the force needed. C. requires a smaller force. D. requires the same force.

Points Earned: 1/1

Correct Answer: C

Your Response: C

3. Which of the following is true about momentum?

A. it is a vector B. it is a product of mass times velocity C. impulses are required to change it D. all of the above E. none of the above

Points Earned: 1/1

Correct Answer: D

Your Response: D

4. A stunt person jumps from a tall building onto a large inflated pad. One reason why the pad reduces the force of impact is because

A. the interaction time is reduced B. the interaction time is increased C. the change in velocity is increased D. the change in velocity is decreased

Points Earned: 1/1

Correct Answer: B

Your Response: B

5. Suppose a ping-pong ball and a bowling ball are rolling toward you. Both have the same momentum, and you exert the same force to stop each. How do the time intervals needed to stop them compare?

A. The time interval is greater for the bowling ball. B. The time interval is greater for the ping-pong ball. C. The time intervals are the same for both.

Points Earned: 1/1

Correct Answer: C

Your Response: C

6. A brick falls to the ground. If the time for the collision of the brick and the ground is increased by a factor of 4, the force of the collision with the ground will change by a factor of

A. 4 B. 16 C. 1/4 D. 1/16

Points Earned: 1/1

Correct Answer: C

Your Response: C

7. A baseball batter hits an incoming 40 m/s fastball. The ball leaves the bat at 50 m/s after a ball-on-bat contact time of 0.03 s. What is the force exerted on the 0.15 kg baseball?

A. 450 N B. 250 N C. 200 N D. 90 N

Points Earned: 1/1

Correct Answer: A

Your Response: A

8. A boy on a sled is moving with an initial momentum of 200 Ns. A force of 12.0 N must be applied for _____ s in order to change the momentum by 70.0 Ns.

A. 840 B. 5.83 C. 16.7 D. 10.8

Points Earned: 1/1

Correct Answer: B

Your Response: B

9. A 0.06 kg tennis ball, initially moving at a speed of 12 m/s, is struck by a racket causing it to rebound in the opposite direction at a speed of 18 m/s. What is the change of momentum of the ball?

A. 0.36 kg m/s B. 0.72 kg m/s C. 1.08 kg m/s D. 1.80 kg m/s

Points Earned: 1/1

Correct Answer: D

Your Response: D

10. A 3-kg bird is flying with a speed of 6 m/s. What is the magnitude of the momentum of the bird?

A. 6 m/s B. 18 kg.m/s C. 18 m/s D. 6 kg.m/s

Points Earned: 1/1

Correct Answer: B

Your Response: B

11. A tennis ball is hit with a tennis racket and the change in the momentum of the ball is 4 kg m/s. If the collision time of the ball and racket is 0.01 seconds, what is the magnitude of the force exerted by the ball on the racket?

A. 0.0025 N B. 0.04 N C. 3.99 N D. 400 N E. none of them

Points Earned: 1/1

Correct Answer: D

Your Response: D

12. Which of the following has the greatest momentum?

A. truck with a mass of 2250 kg moving at a velocity of 25 m/s B. car with a mass of 1210 kg moving at a velocity of 51 m/s C. truck with a mass of 6120 kg moving at a velocity of 10 m/s D. car with a mass of 1540 kg moving at a velocity of 38 m/s

Points Earned: 1/1

Correct Answer: B

Your Response: B

13. The impulse experienced by a body is equivalent to the body’s change in

A. velocity. B. kinetic energy. C. momentum. D. force.

Points Earned: 1/1

Correct Answer: C

Your Response: C

Test 4Your response has been submitted successfully.

Points Awarded  27

Points Missed  0

Percentage  100%

1. A piece of putty and a tennis ball of equal mass are thrown against a wall with the same speed. If the tennis ball bounces off with the same speed but the putty sticks to the wall, then

A. the golf ball undergoes the greatest change of momentum B. the putty undergoes the greatest change of momentum C. the change in momentum for each is the same D. the change depends on the angle of impact

Points Earned: 1/1

Correct Answer: A

Your Response: A

2. It is impossible for an object to have zero momentum if it

A. has acceleration B. has mass C. has velocity D. has potential energy.

Points Earned: 1/1

Correct Answer: C

Your Response: C

3. The momentum of an object is defined as the object’s

A. mass times it acceleration. B. mass times its velocity. C. force times its acceleration. D. force times the time interval. E. velocity times the time interval.

Points Earned: 1/1

Correct Answer: B

Your Response: B

4. The change in an object’s momentum is equal to

A. the product of the mass of the object and the time interval. B. the product of the force applied to the object and the time interval. C. the time interval divided by the net external force. D. the net external force divided by the time interval.

Points Earned: 1/1

Correct Answer: B

Your Response: B

5. A force is applied to stop a moving shopping cart. Increasing the time interval over which the force is applied

A. requires a greater force. B. has no effect on the force needed. C. requires a smaller force. D. requires the same force.

Points Earned: 1/1

Correct Answer: C

Your Response: C

6. Which is a vector?

A. linear momentum B. impulse C. neither a nor b D. both a and b

Points Earned: 1/1

Correct Answer: D

Your Response: D

7. A 1.5 kg ball falls onto a floor. Just before it strikes the floor, its velocity is 12 m/s. The ball bounces up with a velocity of 10 m/s. Find the impulse on the ball.

A. 3 N-s B. 15 N-s C. 18 N-s D. 33 N-s

Points Earned: 1/1

Correct Answer: D

Your Response: D

8. The driver of a 2000 kg car moving at 30 m/s presses on the break pedal. If the braking force is 10,000 N, how far does the car travel before stopping?

A. 45 m B. 90 m C. 135 m D. 180 m

Points Earned: 1/1

Correct Answer: B

Your Response: B

9. Four masses are placed in the xy plane. Determine the coordinates of the center of mass of the system if a 2.00 kg mass is placed at (4,0), a 1.00 kg mass is placed at (3,0), a 3 kg mass is placed at (-1,-1) and a 4.00 kg mass is placed at (-1,-2).

A. (4,0) B. (4,-7) C. (0.4,-0.7) D. (-0.4,0)

Points Earned: 1/1

Correct Answer: C

Your Response: C

10. A barefoot field-goal kicker imparts a velocity of 30 m/s to a football at rest. If the football has a mass of 0.5 kg and time-of-contact with the football is 0.025 s, what is the force exerted on the foot?

A. 188 N B. 375 N C. 600 N D. 900 N

Points Earned: 1/1

Correct Answer: C

Your Response: C

11. What is the momentum of a 2000 kg truck traveling at 20 m/s?

A. 1.0X102 kg˙m/s B. 2.0X104 kg˙m/s C. 4.0X104 kg˙m/s D. 4.0X105 kg˙m/s

Points Earned: 1/1

Correct Answer: C

Your Response: C

12. 0.60-kg tennis ball, initially moving at a speed of 12 m/s, is struck by a racket causing it to rebound in the opposite direction at a speed of 18 m/s. What is the change in momentum of the ball?

A. 0.36 kg˙m/s B. 0.72 kg˙m/s C. 1.1 kg˙m/s D. 1.8 kg˙m/s

Points Earned: 1/1

Correct Answer: D

Your Response: D

13. A 0.2 baseball if pitched with a velocity of 40 m/s and is then batted to the pitcher with a velocity of 60 m/s. What is the magnitude of change in the ball’s momentum?

A. 4 kg*m/s B. 8 kg*m/s C. 2 kg*m/s D. 20 kg*m/s

Points Earned: 1/1

Correct Answer: D

Your Response: D

14. Momentum of a system is conserved only when

A. there are no forces acting on the system. B. there is no external forces acting on the system. C. there are no internal forces acting on the system. D. the system is not moving. E. the system has been moving long enough to gain momentum.

F. none of these

Points Earned: 1/1

Correct Answer: B

Your Response: B

15. An elephant is hit by a ping pong ball. The magnitude of the change in momentum is

A. greatest for the elephant B. greatest for the ping pong ball C. the same for both D. depends on the ratio of the masses of the ball and elephant E. none of these

Points Earned: 1/1

Correct Answer: C

Your Response: C

16.  

A train car that is carrying half its capacity of cargo is moving north on train tracks when it collides with a stationary train car that is loaded to its capacity. The collision is elastic. After the collision,…

A. the half-loaded car is stationary and the fully loaded car moves north with the speed of the original car.

B. the half-loaded car is stationary, and the fully loaded car moves north with half the speed of the original car.

C. the half-loaded car rebounds from the collision back the way it came and the fully loaded car moves northward slowly.

D. the half-loaded car rebounds from the collision back the way it came and the fully loaded car moves northward very fast.

E. both the cars move towards the north, the half-loaded car more slowly than the fully loaded car.

Points Earned: 1/1

Correct Answer: C

Your Response: C

17. If a two-body collision is not head-on, then which of the following may always be

assumed?

A. momentum is conserved B. kinetic energy is conserved C. neither momentum nor kinetic energy are conserved D. both momentum and kinetic energy are conserved

Points Earned: 1/1

Correct Answer: A

Your Response: A

18. After colliding, objects are deformed and lose some kinetic energy. Identify the type of collision.

A. elastic B. perfectly elastic C. inelastic D. perfectly inelastic

Points Earned: 1/1

Correct Answer: C

Your Response: C

19. A 100-kg football linebacker moving at 2 m/s tackles head-on an 80-kg halfback running 3 m/s. Neglecting the effects due to digging in of cleats,

A. the linebacker will drive the halfback backward. B. the halfback will drive the linebacker backward. C. neither player will drive the other backward. D. this is a simple example of an elastic collision.

Points Earned: 1/1

Correct Answer: B

Your Response: B

20. A 1000 kg car traveling east at 20 m/s collides head on with a 1500 kg car traveling west at 10 m/s. The cars stick together after the collision. What is their common velocity after the collision?

A. 3 m/s east B. 4 m/s east C. 6 m/s west D. 14 m/s east E. none of these

Points Earned: 1/1

Correct Answer: E

Your Response: E

21. A large platform is initially at rest on an a smooth surface. A dog on the platform starts running toward the east. The mass of the dog is one-half the mass of the platform. When the dog moves toward the east with a speed vo, the platform moves toward the ________ with a speed ________.

A. east ... vo/2 B. east ... 2 vo C. west ... vo/2 D. west ... 2 vo E. none of these

Points Earned: 1/1

Correct Answer: C

Your Response: C

22. Two children on ice skates push off from each other. If the first child has mass 40 kg and pushes off with speed of 5 m/s. How fast is the other child moving if she has a mass of 50 kg?

A. 4 m/s B. 4.5 m/s C. 5 m/s D. 5.9 m/s E. 6.25 m/s

Points Earned: 1/1

Correct Answer: A

Your Response: A

23. A 50-kg pitching machine (excluding the baseball) is placed on a frozen pond. The machine fires a 0.40-kg baseball with a speed of 35 m/s in the horizontal friction. What is the recoil speed of the pitching machine? (Assume negligible friction.)

A. 0.14 m/s B. 0.28 m/s C. 0.70 m/s D. 4.4*103 m/s

Points Earned: 1/1

Correct Answer: B

Your Response: B

24. A bullet moving at 300 m/s is fired into a 1.00-kg block. The bullet emerges (the bullet does not embedded in the block) with half of its original speed. What is the velocity of the block right after the collision?

A. 1.50 m/s B. 97 m/s

C. 3.00 m/s D. 273 m/s E. not enough information given

Points Earned: 1/1

Correct Answer: E

Your Response: E

25. A 75 kg swimmer dives horizontally off a 500 kg raft. If the diver's speed immediately after leaving the raft is 4 m/s, what is the corresponding raft speed?

A. 0.2 m/s B. 0.56 m/s C. 0.6 m/s D. 4 m/s

Points Earned: 1/1

Correct Answer: C

Your Response: C

26. A 1000-kg car, moving at 35 MPH, collides with another car, mass = 1500-kg, at rest. What will be the speed of the two cars just after the collision if they stick together?

A. 23 MPH B. 14 MPH C. 35 MPH D. 14 m/s

Points Earned: 1/1

Correct Answer: B

Your Response: B

27. Daisy (50-kg mass) skates on ice at 4.0 m/s to greet her friend (70-kg mass), who is standing still, with open arms. As they collide, while holding each other, with what speed do they both move off together?

A. Zero B. 1.7 m/s C. 2.5 m/s D. 5.0 m/s

Points Earned: 1/1

Correct Answer: B

Your Response: B