Download MC Chapters 5-8 - MrStapleton.com

Mid-Term Review - Multiple Choice
Chapters 5-8
1) The momentum of an object is defined as the object's __________.
A) force times its acceleration.
B) mass times it acceleration.
C) mass times its velocity.
D) force times the time interval.
E) velocity times the time interval.
2) Which has more momentum, a large truck moving at 30 miles per hour or a small truck moving at 30 miles per
hour?
A) Both have the same momentum.
B) The large truck
C) The small truck
3) The momentum change of an object is equal to the __________.
A) object's mass times the force acting on it.
B) force acting on it.
C) force acting on it times its velocity.
D) impulse acting on it.
E) velocity change of the object.
4) The reason padded dashboards are used in cars is that they __________.
A) decrease the impulse in a collision.
B) increase the time of impact in a collision.
C) increase the force of impact in a collision.
D) decrease the momentum of a collision.
E) look nice and feel good.
5) A Ping-Pong ball launcher is fired. Compared to the force on the ball, the force on the launcher is __________.
A) larger.
B) the same.
C) smaller.
6) A Ping-Pong ball launcher is fired. Compared to the impulse on the ball, the impulse on the launcher is _______.
A) larger.
B) the same.
C) smaller.
7) A cannon recoils from launching a cannonball. The speed of the cannon's recoil is small because the _________.
A) cannon has far more mass than the cannonball.
B) force against the cannon is relatively small.
C) momentum of the cannon is unchanged.
D) impulse on the cannon is less than the impulse on the cannonball.
E) none of the above
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 higher __________.
A) speed.
B) momentum.
C) acceleration.
D) all of the above
E) none of the above
9) In order to catch a ball, a baseball player moves his or her hand backward in the direction of the ball's motion.
Doing this reduces the force of impact on the player's hand principally because __________.
A) the time of impact is increased.
B) the time of impact is decreased.
C) the momentum of impact is reduced.
D) the velocity of the hand is reduced.
E) none of the above
10) A cannon fires a cannonball. The speed of the cannonball will be the same as the speed of the recoiling cannon
__________.
A) if the mass of the cannonball equals the mass of the cannon.
B) because velocity is conserved.
C) because momentum is conserved.
D) because both velocity and momentum are conserved.
E) none of the above
11) When you jump off a step, you usually bend your knees as you reach the ground. By doing this, the time of the
impact is about 10 times more what it would be in a stiff-legged landing and the average force on your body is
reduced by __________.
A) more than 10 times.
B) about 10 times.
C) less than 10 times.
12) A karate expert executes a swift blow and severs a cement block with her bare hand.
A) The impulse on both the block and the expert's hand have the same magnitude.
B) The time of impact on both the block and the expert's hand is the same.
C) The force on both the block and the expert's hand have the same magnitude.
D) all of the above
E) none of the above
13) A moving freight car runs into an identical car at rest on the track. The cars couple together. Compared to the
velocity of the first car before the collision, the velocity of the combined cars after the collision is __________.
A) zero.
B) one half as large.
C) the same.
D) twice as large.
E) More information is needed to say.
14) A 2-kg ball is thrown at 3 m/s. What is the ball's momentum?
A) 3 kg m/s
B) 9 kg m/s
C) 2 kg m/s
D) 6 kg m/s
E) none of the above
15) 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) 48 m/s
D) 12 m/s
E) none of the above
16) In physics, work is defined as __________.
A) force divided by distance.
B) force divided by time.
D) force times time.
E) force times distance.
C) distance divided by time.
17) If you lift two loads up one story, how much work do you do compared to lifting just one load up one story?
A) Twice as much
B) One quarter as much
C) The same amount
D) One half as much
E) Four times as much
18) If you lift one load up two stories, how much work do you do compared to lifting one load up only one story?
A) Twice as much
B) The same amount
C) Four times as much
D) One quarter as much
E) One half as much
19) Power is defined as the __________.
A) force on an object divided by the time the force acts.
B) distance divided by the time taken to move that distance.
C) work done on an object divided by the time taken to do the work.
D) force on an object times the distance the object moves.
E) work done times the time taken to do that work.
20) The unit of power is the __________.
A) newton. B) watt. C) second. D) joule. E) meter.
21) An arrow in a bow has 70 J of potential energy. Assuming no loss of energy due to heat, how much kinetic
energy will it have after it has been shot?
A) 50 J
B) 35 J
C) 70 J
D) 0 J
E) 140 J
22) How much farther will a car traveling at 100 km/s skid than the same car traveling at 50 km/s?
A) Half as far
B) Four times as far
C) Five times as far
D) Twice as far
E) The same distance
23) As a pendulum swings back and forth __________.
A) kinetic energy is transformed into potential energy.
B) potential energy is transformed into kinetic energy.
C) at the lowest part of its swing, its energy is all kinetic.
D) at the end points of its swing, its energy is all potential.
E) all of the above
24) A woman can lift barrels a vertical distance of 1 meter or can roll them up a 2 meter-long ramp to the same
elevation. If she uses the ramp, the applied force required is __________.
A) half as much.
B) one quarter as much.
C) twice as much.
D) the same amount.
E) four times as much.
25) A job is done slowly, and an identical job is done quickly. Both jobs require the same amount of work but
different amounts of __________.
A) power.
B) energy.
C) both A and B
D) none of the above
26) A ball is thrown 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) Not enough information given.
C) 100 J.
D) more than 100 J.
27) The ratio of output force to input force of a simple machine is called the __________.
A) pivot point.
B) fulcrum.
C) mechanical advantage.
D) efficiency.
E) lever arm.
28) All simple machines ideally work on the principle that __________.
A) kinetic energy transforms into potential energy.
B) work input equals work output.
C) total momentum before a collision equals total momentum after the collision.
D) force equals mass times acceleration.
E) impulse equals momentum change.
29) A pulley system can __________.
A) change the direction of a force.
D) Both A and B
B) multiply the force.
E) Both B and C
C) increase the amount of work done.
30) The ratio of useful work output to total work input is called the __________.
A) pivot point.
B) efficiency.
C) lever arm. D) mechanical advantage.
31) How many joules of work are done on an object when a force of 10 N pushes it 5 m?
A) 1 J
B) 50 J
C) 5 J
D) 2 J
E) 10 J
E) fulcrum.
32) How much power is required to do 100 J of work on an object in 2 seconds?
A) 0 W
B) 50 W
C) 2 W
D) 100 W
E) 200 W
33) A girl can easily lift an 80-N rock with the help of a lever. When she pushes down with 10 N of force, she lifts
the rock 0.1 meters. How far does she move her arms to do this?
A) 10 m
B) 0.8 m
C) 8 m
D) 0.1 m
E) 1 m
34) If Kelly the skater's speed increases so he has twice the momentum, then his kinetic energy increases by
__________.
A) eight times.
B) two times.
C) four times.
D) none of the above (KE remains the same.)
35) A pulley has two supporting strands. In order to use it to lift a load 1 meter, the person pulling will have to pull
a distance of __________.
A) 1/4 m.
B) 4 m.
C) 1 m.
D) 2 m.
E) 1/2 m.
36) A frictionless inclined plane is 6 m long and rests on a wall that is 2 m high. How much force is needed to push
a block of ice weighing 300 N up the plane?
A) 300 N
B) 50 N
C) 100 N
D) 200 N
E) 600 N
37) A certain jack has a theoretical mechanical advantage of 500. However, due to frictional forces, the actual
mechanical advantage is only 100. What is the efficiency of the jack?
A) 1/5
B) 500
C) 5
D) 50 000
E) 50
38) A machine puts out 100 watts of power for every 1000 watts put into it. The efficiency of the machine is
__________.
A) 50%.
B) 90%.
C) 110%.
D) 10%.
E) none of the above
39) How much work is done on a 50-N rock that you carry horizontally across a 10-m room?
A) 10 J
B) 5 J
C) 500 J
D) 0 J
E) 50 J
40) Which requires more work: lifting a 50-kg sack vertically 2 meters or lifting a 25-kg sack vertically 4 meters?
A) Lifting the 25-kg sack
B) Lifting the 50-kg sack
C) Both require the same amount of work.
Answers:
1) C
8) B
15) A
22) B
29) D
36) C
2) B
9) A
16) E
23) E
30) B
37) A
3) D
10) A
17) A
24) A
31) B
38) D
4) B
11) B
18) A
25) A
32) B
39) D
5) B
12) D
19) C
26) A
33) B
40) C
6) B
13) B
20) B
27) C
34) C
7) A
14) D
21) C
28) B
35) D