Answers350CR Integrated ScienceWork and Power

Work and Power Answers

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1
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In which scenario is the least amount of work done on a crate?

A
A force of 120 N moves it 25 m.
B
A force of 115 N moves it 26 m.
C
A force of 130 N moves it 22 m.
D
A force of 125 N moves it 27 m.
2
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Examine the scenarios.Scenario W: A force of 75 N moves a box 15 m.Scenario X: A force of 100 N moves a box 12 m.Scenario Y: A force of 50 N moves a box 20 m.Scenario Z: A force of 25 N moves a box 45 m.

A
W and X
B
W and Z
C
X and Y
D
Y and Z
3

In which scenario is an animal doing work? Check all that apply.A cat lifts up her kitten by its neck.A dog rubs his back against a large tree.A bird flies a worm from the ground to its nest in a tree.A goat butts its head against the barn wall.A horse pulls a wagon along a road.

A
A cat lifts up her kitten by its neck.
B
A dog rubs his back against a large tree.
C
A bird flies a worm from the ground to its nest in a tree.
D
A goat butts its head against the barn wall.
E
A horse pulls a wagon along a road.
4

A 5,400 W motor is used to do work. If the motor is used for 640 s, about how much work could it do?

A
8.4 J
B
4,800 J
C
6,000 J
D
3,500,000 J
5

A 2.50 × 105 W motor is used for 26.4 s to pull a boat straight toward shore. How far does the boat move toward shore if a force of 4.20 × 104 N is applied by the motor?

A
157 m
B
1,590 m
C
1.11 × 106 m
D
6.60 × 106 m
6

A load of bricks is lifted to the second floor of a building. How do work and power relate to this job?

A
The longer the job takes, the more work is done.
B
The faster the job is done, the greater the power.
C
The greater the power applied, the more work is done.
D
The less work is done, the more power is needed.
7

Natalia lifts a bag of groceries 0.50 m by exerting a force of 36 N. How much work did she do on the bag?

A
0 J
B
18 J
C
36 J
D
72 J
8

Lester prepares to lift a heavy sack of flour into a customer’s shopping cart. During which part of the action does Lester do work?

A
when he applies force to the sack before lifting it
B
when he holds the sack against his chest
C
as he lets go of the sack and it falls onto a cart
D
as he lifts the sack to his chest from the floor
9

Which best identifies the requirements for work to be performed?

A
an object that has a force acting on it
B
an object that is moving and has no net force
C
a force acting on a motionless object
D
a force that moves an object
10

Trevor is pulling his younger brother in a wagon. He pulls the wagon 50 m to the corner with a force that is parallel with the ground. He then turns the wagon around and pulls it 50 m back to the starting point with the same force at an angle of 30° with respect to the ground.

A
They are the same because he uses the same amount of force.
B
They are the same because he travels the same distance.
C
He does less work coming back because the force moving the wagon is only 50cos30°.
D
He does more work coming back because the force moving the wagon is only 50cos60°.
11

How do the units of work and power compare?

A
The unit for work is a watt. The unit for power is a joule, which is a watt-second.
B
The unit for work is a watt. The unit for power is a joule, which is a watt per second.
C
The unit for work is a joule. The unit for power is a watt, which is a joule-second.
D
The unit for work is a joule. The unit for power is a watt, which is a joule per second.
12

Which statement about work and power correctly describes an automobile race?

A
The cars do different amounts of work depending on how fast they finish.
B
The car that finishes last has the lowest power.
C
The car with the greatest power travels the greatest distance.
D
The cars do different amounts of work depending on their power.
13

Brandi poses as Lady Justice for a skit in her government class. She holds a set of scales above her head with her right hand and a sword by her side in her left hand. She holds the pose for 10 minutes. At the end of the skit, she mentions to her friend that it was a lot of work to pose and that her arms were really tired.

A
She did no work because she did not exert any forces on objects.
B
She did more work using her right hand than her left because her right hand was higher.
C
She did no work because she did not move the scales or sword while she posed.
D
She did work the entire time she posed because she was tired at the end.
14

What is the unit for work?

A
watt
B
joule
C
newton
D
meter
15

The use of force to move an object is .

Answer not available
16

How is power calculated?

A
multiply force and displacement
B
divide force by displacement
C
multiply work and time
D
divide work by time
17

Hiro walks up a flight of stairs in his apartment building. Later in the day, he runs up the same flight of stairs.

A
He did more work running than walking.
B
He did more work walking than running.
C
He had more power running than walking.
D
He had more power walking than running.
18

A force of 75 N at an angle of 15° to the direction of motion moves a chair 3 m. Which change would result in more work being done on the chair?

A
using 60 N of force
B
moving the chair 2 m
C
increasing the angle to 20°
D
decreasing the angle to 10°

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