Question 1

Which task requires more work?

Accepted Answer

A) lifting the 50-kg sack 2 meters 
B) lifting the 25-kg sack 4 meters 
C) both require the same 
D) need more information 
A) lifting the 50-kg sack 2 meters 
B) lifting the 25-kg sack 4 meters 
C) both require the same 
D) need more information

Question 2

When a drawn bow of potential energy 40 J is fired, the arrow will ideally have a kinetic energy

Accepted Answer

A) less than 40 J. 
B) more than 40 J. 
C) of 40 J. 
A) less than 40 J. 
B) more than 40 J. 
C) of 40 J.

Question 3

The center of a long uniform log is raised to shoulder level while the other end is on the ground. If instead, the end of the log is raised to shoulder level, the work required is

Accepted Answer

A) half. 
B) the same. 
C) twice. 
A) half. 
B) the same. 
C) twice.

Question 4

If an all-electric car has kinetic energy, then it also must have

Accepted Answer

A) impulse. 
B) momentum. 
C) acceleration. 
D) force. 
E) none of the above 
A) impulse. 
B) momentum. 
C) acceleration. 
D) force. 
E) none of the above

Question 5

A car's engine is 20% efficient. When cruising, the car encounters an average retarding force of 1000 N. If the energy content of fuel is 40 megajoules per liter, how many kilometers per liter does the car achieve?

Accepted Answer

A) 8 
B) 10 
C) 12 
D) 14 
E) none of the above 
A) 8 
B) 10 
C) 12 
D) 14 
E) none of the above

Question 6

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

Question 7

The power required to exert 4-N force over 3 meters in 2 seconds is

Accepted Answer

A) 4 W. 
B) 6 W. 
C) 8 W. 
D) 12 W. 
E) none of the above 
A) 4 W. 
B) 6 W. 
C) 8 W. 
D) 12 W. 
E) none of the above

Question 8

Two identical particles move toward each other, one twice as fast as the other. Just before they collide, one has a kinetic energy of 25 J and the other 50 J. At this instant their total kinetic energy is

Accepted Answer

A) 25 J. 
B) 50 J. 
C) 75 J. 
D) none of the above 
E) need more information 
A) 25 J. 
B) 50 J. 
C) 75 J. 
D) none of the above 
E) need more information

Question 9

A miracle car with a 100% efficient engine burns fuel having a 40-megajoules-per-liter energy content. If air drag and overall frictional forces at highway speeds totals 1000 N, what distance per liter can be achieved on the highway?

Accepted Answer

A) 30 km 
B) 40 km 
C) 50 km 
D) more than 50 km 
E) need more information 
A) 30 km 
B) 40 km 
C) 50 km 
D) more than 50 km 
E) need more information

Question 10

The unit kilowatt-hour is a unit of

Accepted Answer

A) energy. 
B) momentum. 
C) power. 
D) time. 
A) energy. 
B) momentum. 
C) power. 
D) time.

Question 11

Impulse involves the time that a force acts, whereas work involves the

Accepted Answer

A) distance that a force acts. 
B) time and distance that a force acts. 
C) acceleration that a force produces. 
A) distance that a force acts. 
B) time and distance that a force acts. 
C) acceleration that a force produces.

Question 12

A roller skate at rest may have

Accepted Answer

A) speed. 
B) velocity. 
C) momentum. 
D) energy. 
A) speed. 
B) velocity. 
C) momentum. 
D) energy.

Question 13

Earth's primary energy source is

Accepted Answer

A) the Sun. 
B) fossil fuel. 
C) electricity. 
D) geothermal. 
A) the Sun. 
B) fossil fuel. 
C) electricity. 
D) geothermal.

Question 14

A hydraulic press, like an inclined plane, is capable of increasing energy.

Accepted Answer

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

Question 15

If a Ping-Pong ball and a golf ball both move in the same direction with the same amount of kinetic energy, the speed of the Ping-Pong ball must be

Accepted Answer

A) less than the golf ball. 
B) more than the golf ball. 
C) both the same 
D) need more information 
A) less than the golf ball. 
B) more than the golf ball. 
C) both the same 
D) need more information

Question 16

The work you do when pushing a shopping cart a given distance while applying twice as much force is

Accepted Answer

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

Question 17

Two identical golf carts move at different speeds. The faster cart has twice the speed and therefore has

Accepted Answer

A) twice the kinetic energy. 
B) four times the kinetic energy. 
C) eight times the kinetic energy. 
D) none of the above 
A) twice the kinetic energy. 
B) four times the kinetic energy. 
C) eight times the kinetic energy. 
D) none of the above

Question 18

A 1-kg ball dropped from 2 m rebounds only 1.5 m after hitting the ground. The amount of energy converted to heat is about

Accepted Answer

A) 0.5 J. 
B) 1.0 J. 
C) 1.5 J. 
D) 2.0 J. 
E) more than 2.0 J. 
A) 0.5 J. 
B) 1.0 J. 
C) 1.5 J. 
D) 2.0 J. 
E) more than 2.0 J.

Question 19

A piece of taffy slams into and sticks to an identical piece of taffy at rest. The momentum of the combined pieces after the collision is the same as before the collision, but this is not true of the kinetic energy, which partly degrades into heat. What percentage of the kinetic energy becomes heat?

Accepted Answer

A) 0% 
B) 25% 
C) 50% 
D) 75% 
E) need more information 
A) 0% 
B) 25% 
C) 50% 
D) 75% 
E) need more information

Question 20

The power expended doing 100 J of work in 50 s is

Accepted Answer

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

Exam 7: Energy

Which task requires more work?

When a drawn bow of potential energy 40 J is fired, the arrow will ideally have a kinetic energy

The center of a long uniform log is raised to shoulder level while the other end is on the ground. If instead, the end of the log is raised to shoulder level, the work required is

If an all-electric car has kinetic energy, then it also must have

A car's engine is 20% efficient. When cruising, the car encounters an average retarding force of 1000 N. If the energy content of fuel is 40 megajoules per liter, how many kilometers per liter does the car achieve?

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

The power required to exert 4-N force over 3 meters in 2 seconds is

Two identical particles move toward each other, one twice as fast as the other. Just before they collide, one has a kinetic energy of 25 J and the other 50 J. At this instant their total kinetic energy is

A miracle car with a 100% efficient engine burns fuel having a 40-megajoules-per-liter energy content. If air drag and overall frictional forces at highway speeds totals 1000 N, what distance per liter can be achieved on the highway?

The unit kilowatt-hour is a unit of

Impulse involves the time that a force acts, whereas work involves the

A roller skate at rest may have

Earth's primary energy source is

A hydraulic press, like an inclined plane, is capable of increasing energy.

If a Ping-Pong ball and a golf ball both move in the same direction with the same amount of kinetic energy, the speed of the Ping-Pong ball must be

The work you do when pushing a shopping cart a given distance while applying twice as much force is

Two identical golf carts move at different speeds. The faster cart has twice the speed and therefore has

A 1-kg ball dropped from 2 m rebounds only 1.5 m after hitting the ground. The amount of energy converted to heat is about

The power expended doing 100 J of work in 50 s is

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