Deck 13: Energy and Power

Question 1

What is the SI unit for work?

A)Newton
B)Watt
C)Kelvin
D)Joule

Answer 1

D

Question 2

In the following equation, what does the x stand for? $$\text { elastic energy } = \frac { 1 } { 2 } k x ^ { 2 }$$

A)deflection of spring from its unstretched position
B)original length of unstretched spring
C)spring force
D)a generic unknown quantity

Answer 2

deflection of spring from its unstretched position

Question 3

Work is found by multiplying force by what other physical quantity?

A)distance
B)mass
C)power
D)time

Answer 3

A

Question 4

A ping pong ball and a bowling ball are moving with the same momentum.Which has the greater kinetic energy?

A)The ping pong ball
B)The bowling ball

Question 5

A stone is dropped from a bridge and allowed to free-fall downward.As it falls a certain distance its gravitational potential energy decreases by 1000J.By how much does the stone's
Kinetic energy increase? (Neglect air resistance.)

Question 6

While driving down the highway, your car must overcome the forces of friction and air
necessary to keep a car moving at a constant speed.While driving the car a distance of
100,000m, the car burns up 10.6 liters of gasoline.If gasoline contains 100,000,000 joules of
potential energy per liter, what is the efficiency of the car's engine?

Question 7

What is the SI unit for elastic energy?

A)Newton
B)Watt
C)Kelvin
D)Joule

Question 8

Energy is a fundamental dimension.

Question 9

Which produces the greater change in kinetic energy (assume that all of the work goes into kinetic energy):

Question 10

In the absence if heat transfer, and assuming negligible losses and no work, conservation of mechanical energy states that the total mechanical energy of a system is

A)increasing
B)constant
C)decreasing
D)decreasing, then constant

Question 11

Which of the following requires the most work done by the brakes of a car?

A)slowing down from 80 kmph to 55 kmph
B)stopping from 55 kmph
C)equal amounts of work for both

Question 12

In the following equation, what does the k stand for? $$\text { elastic energy } = \frac { 1 } { 2 } k x ^ { 2 }$$

A)kinetic energy
B)spring constant
C)elastic constant
D)momentum

Question 13

While using a push mower to mow your lawn, you notice that you push with a constant
horizontal force of 75N .How much work do you do while pushing the lawn mower a total
distance of on level ground?

Question 14

How much kinetic energy does a 3kg soccer ball have while moving at toward your opponents' goal?

Question 15

What is the SI unit for kinetic energy?

A)Newton
B)Watt
C)Kelvin
D)Joule

Question 16

The sketch below shows a bowling ball return at a bowling alley.Estimate the required
speed of the ball at point 1 so that it reaches point 2 with a speed of .Point 2 is a height of

Question 17

How much kinetic energy does a soccer ball have while moving at toward your goal?

Question 18

The change in gravitational potential energy is found by multiplying an object's change in elevation by its

A)mass
B)weight
C)density
D)height

Question 19

Power is a fundamental dimension.

Question 20

What is the SI unit for gravitational potential energy?

A)Newton
B)Watt
C)Kelvin
D)Joule

Question 21

The largest source of electric power in the United States is

A)solar
B)natural gas
C)nuclear
D)coal
E)hydroelectric

Question 22

In general, efficiency is defined as

A)output divided by input
B)input divided by output
C)output multiplied by input
D)output minus input

Question 23

Power can be described as

A)how hard you push
B)how fast you push
C)how far you push
D)how long you push

Question 24

The time rate of doing work is called

A)energy
B)power
C)force
D)momentum

Question 25

A team is more powerful than an individual because

A)the team can do more work than the individual in the same amount of time
B)the team can do the same amount of work as the individual, but in less time
C)the team can do more work than the individual in less time
D)All of the above.

Question 26

Power is found by dividing work by what other physical quantity?

A)distance
B)mass
C)force
D)time

Question 27

What is the SI unit for heat?

A)Kelvin
B)Celsius
C)Joule
D)Watt

Question 28

The law that simply states that energy is conserved is

Question 29

The SI unit for power is

A)watt
B)joule
C)newton
D)horsepower

Question 30

75 meters above point 1.Neglect rolling friction and air resistance.

Question 31

Thermal energy transfer is called

A)temperature difference
B)heat difference
C)temperature flux
D)heat