North Carolina Science Grade 7

Chapter 14: Work and Simple Machines

Work and Simple Machines

1.
How do input force and output force relate to each other?
A)They are the same.
B)They are unrelated.
C)The input is always less than the output.
D)They are always different.
2.
A 5,000 N block was lifted 10 m. How much work was done?
A)50 J
B)500 J
C)50,000 J
D)5,000 J
3.
A chisel is an example of which machine?
A)pulley
B)wheel and axle
C)lever
D)wedge
4.
What happens to the amount of power expended when you are climbing stairs and then climb faster?
A)It increases.
B)It stays the same.
C)It stops.
D)It decreases.
5.
The efficiency of all machines is __________.
A)exactly 100 percent
B)more than 100 percent
C)impossible to calculate
D)less than 100 percent
6.
What does a screw consist of?
A)an inclined plane wrapped around a cylinder
B)a lever wrapped around a pole
C)a wedge wrapped around a pipe
D)a wheel and axle in a vertical position
7.
What is transferred when work is done?
A)matter
B)mass
C)velocity
D)energy
8.
A drill bit is an example of which type of machine?
A)wheel and axle
B)screw
C)pulley
D)lever
9.
What is the scientific formula for work?
A)W = F x d
B)W = F + d
C)W = F/d
D)W = F - d
10.
When you climb stairs and then walk down a hallway, in which direction is the work done?
A)along the hallway
B)in the opposite direction that you walk
C)downward
D)upward
11.
What is the mechanical advantage if 50 J are put in and 200 J are produced?
A)200
B)4
C)1000
D)50
12.
What is a sign that work is being done?
A)density
B)matter
C)motion
D)mass
13.
Which is an example of work being done in a scientific sense?
A)pushing against a stationary box
B)doing homework
C)lifting a box
D)carrying a box
14.
Power is measured by which units?
A)newton-meters
B)watts
C)joules
D)newtons
15.
Mechanical advantage is equal to __________.
A)input force times output force
B)output force times input force
C)output force divided by input force
D)input force divided by output force
16.
Using several pulleys together is known as a __________.
A)pulley group
B)machine system
C)wheel and axle
D)pulley system
17.
The unit for work is a joule, which is equal to __________.
A)N - m
B)N/m
C)N + m
D)N x m
18.
Which simple machines are found on a hammer?
A)plane and lever
B)wedge and plane
C)screw and pulley
D)lever only
19.
Which of the following do you think a wheel and axle is most closely related to?
A)inclined plane
B)wedge
C)lever
D)pulley
20.
On what point does a lever pivot?
A)the middle
B)the arm
C)the fulcrum
D)the end
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