Question 1

Do 100 J of work in 50 s and your power output is

Accepted Answer

A)  1/2 W
B)  2 W.
C)  4 W.
D)  50 W.
E)  5,000 W.

Question 2

A bow is drawn so that it has 40 J of potential energy.When fired,the arrow will ideally have a kinetic energy that is

Accepted Answer

A)  less than 40 J.
B)  more than 40 J.
C)  40 J.
D)  impossible to predict without additional information

Question 3

A ball rolling down an incline has its minimum speed

Accepted Answer

A)  at the end the incline.
B)  half way down the incline.
C)  near the top of the incline.
D)  impossible to predict without knowing the ball's mass
E)  impossible to predict without knowing the size of the ball

Question 4

Using 1000 J of work,a toy elevator is raised from the ground floor to the second floor in 20 seconds.The power needed to do this job was

Accepted Answer

A)  20 W.
B)  50 W.
C)  100 W.
D)  1000 W.
E)  20,000 W.

Question 5

What task requires the most work;lifting a 50-kg sack 2 meters or lifting a 25-kg sack 4 meters?

Accepted Answer

A)  the 50-kg sack
B)  the 25-kg sack
C)  Both require the same amount of work.
D)  impossible to determine without knowing the contents of the sack

Question 6

A 2 kg mass has 40 J of potential energy with respect to the ground.Approximately how high is it above the ground?

Accepted Answer

A)  1 m
B)  2 m
C)  3 m
D)  4 m
E)  none of these

Question 7

A TV set is pushed a distance of 2 m with a force of 20 N.How much work is done on the set?

Accepted Answer

A)  2 J
B)  10 J
C)  20 J
D)  40 J
E)  800 J

Question 8

A woman carries a heavy box across a room at a constant speed.How much work does she do on the box while walking?

Accepted Answer

A)  none
B)  More information is needed about the weight of the box.
C)  More information is needed about the distance walked.
D)  More information is needed about the speed and the distance.
E)  More information is needed about the weight,distance,and her speed.

Question 9

A ball rolling down an incline has its maximum kinetic energy at

Accepted Answer

A)  the top.
B)  halfway down.
C)  three-quarters of the way down.
D)  the bottom.

Question 10

If you push an object a given distance,while applying twice the force,you do

Accepted Answer

A)  twice as much work.
B)  four times as much work.
C)  the same amount of work.
D)  half as much work.

Question 11

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?

Accepted Answer

A)  6 J
B)  8 J
C)  32 J
D)  80 J
E)  none of these

Question 12

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

Accepted Answer

A)  less than 100 J.
B)  more than 100 J.
C)  100 J.
D)  not enough information given

Question 13

Both a 50-kg sack is lifted 2 meters from the ground and a 25-kg sack is lifted 4 meters in the same time.The power expended in raising the 50-kg sack is

Accepted Answer

A)  twice as much.
B)  half as much.
C)  the same.
D)  impossible to predict without further information

Question 14

When properly used,a hydraulic press,like a wheel and axle,is capable of multiplying force input.

Accepted Answer

A)  always true
B)  always false
C)  sometimes true
D)  sometimes false

Question 15

No work is done by gravity on a bowling ball that rolls along a bowling alley because

Accepted Answer

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.

Question 16

A car that travels twice as fast as another when braking to a stop will skid

Accepted Answer

A)  twice as far.
B)  four times as far.
C)  depends on the mass of the cars

Question 17

Two identical freight cars roll without friction (one at 1 m/s,the other at 2 m/s) toward each other on a level track.They collide,couple together,and roll away in the direction that

Accepted Answer

A)  the slower car was initially going.
B)  the faster car was initially going.
C)  Neither of these.They stop.

Question 18

An object lifted 10 meters gains 200 J of potential energy.If the same object is lifted 20 meters,its potential energy gain is

Accepted Answer

A)  half as much.
B)  the same.
C)  twice as much.
D)  four times as much.
E)  more than four times as much.

Question 19

Two identical arrows,one with twice the kinetic energy of the other,are fired into a hay bale.The faster arrow will penetrate

Accepted Answer

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

Question 20

A moving object has

Accepted Answer

A)  speed.
B)  velocity.
C)  momentum.
D)  energy.
E)  all of these

Exam 7: Energy

Using 1000 J of work,a toy elevator is raised from the ground floor to the second floor in 20 seconds.The power needed to do this job was

Correct AnswerverifiedShow Answer

A car that travels twice as fast as another when braking to a stop will skid

Correct AnswerverifiedShow Answer

Do 100 J of work in 50 s and your power output is

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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?

Correct AnswerverifiedShow Answer

A moving object has

Correct AnswerverifiedShow Answer

Two identical freight cars roll without friction (one at 1 m/s,the other at 2 m/s) toward each other on a level track.They collide,couple together,and roll away in the direction that

Correct AnswerverifiedShow Answer

When properly used,a hydraulic press,like a wheel and axle,is capable of multiplying force input.

Correct AnswerverifiedShow Answer

What task requires the most work;lifting a 50-kg sack 2 meters or lifting a 25-kg sack 4 meters?

Correct AnswerverifiedShow Answer

A ball rolling down an incline has its maximum kinetic energy at

Correct AnswerverifiedShow Answer

Both a 50-kg sack is lifted 2 meters from the ground and a 25-kg sack is lifted 4 meters in the same time.The power expended in raising the 50-kg sack is

Correct AnswerverifiedShow Answer

A 2 kg mass has 40 J of potential energy with respect to the ground.Approximately how high is it above the ground?

Correct AnswerverifiedShow Answer

A bow is drawn so that it has 40 J of potential energy.When fired,the arrow will ideally have a kinetic energy that is

Correct AnswerverifiedShow Answer

A woman carries a heavy box across a room at a constant speed.How much work does she do on the box while walking?

Correct AnswerverifiedShow Answer

If you push an object a given distance,while applying twice the force,you do

Correct AnswerverifiedShow Answer

A ball rolling down an incline has its minimum speed

Correct AnswerverifiedShow Answer

An object lifted 10 meters gains 200 J of potential energy.If the same object is lifted 20 meters,its potential energy gain is

Correct AnswerverifiedShow Answer

A TV set is pushed a distance of 2 m with a force of 20 N.How much work is done on the set?

Correct AnswerverifiedShow Answer

No work is done by gravity on a bowling ball that rolls along a bowling alley because

Correct AnswerverifiedShow Answer

Two identical arrows,one with twice the kinetic energy of the other,are fired into a hay bale.The faster arrow will penetrate

Correct AnswerverifiedShow Answer

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