Chapter 5:
Machines
Practice Test
1.
What is the mechanical advantage of a lever if the effort arm is 2.0 m long and the resistance arm is 0.5 m long?
a.
impossible to calculate with the information provided
b.
0.25
c.
4[.0]
d.
1[.0]
Hint
2.
Suppose you need to place a 5-kg block of ice onto the shelf of a freezer 2.0 m high. The ice will soon start melting, so you must place the ice in the freezer in 10 s. How much power will you need?
a.
10 W
b.
1 W
c.
25 W
d.
2.5 W
Hint
3.
When using a wheel and axle, what happens as the size of the wheel increases?
a.
You need more effort force to turn the axle.
b.
The amount of work you must do is less.
c.
You need less effort force to turn the axle.
d.
The distance the axle moves as you turn the wheel increases.
Hint
4.
What is the science of making machines suitable for the people who use them?
a.
ergonomics
b.
biotechnology
c.
economics
d.
tectonics
Hint
5.
How are work, power, and time related?
a.
Work is time over power.
b.
Power is work over time.
c.
Work is power over time.
d.
Time is power over work.
Hint
6.
What is the basic advantage of single fixed pulley?
a.
The pulley decreases the amount of work needed to move an object.
b.
The force exerted is reduced compared to the resistance force.
c.
The pulley changes the direction of the effort force.
d.
The pulley changes the distance over which the effort force is applied.
Hint
7.
What does the mechanical advantage of a machine tell you?
a.
how much bigger resistance force is compared to effort force
b.
how much the effort force is multiplied
c.
how useful a machine may be
d.
All of the above are correct.
Hint
8.
How can you increase the efficiency of a machine?
a.
by decreasing the work input to the machine without increasing output
b.
by reducing losses due to friction
c.
how useful a machine may be
d.
All of the above.
Hint
9.
A screw and a wedge are both similar to what other kind of simple machine?
a.
a wheel and axle
b.
a pulley
c.
a lever
d.
an inclined plane
Hint
10.
What is the basic principle of using a lever?
a.
The resistance force is greater than the effort force.
b.
You exert a small force over a long distance.
c.
The amount of work the lever performs is more than the work you perform.
d.
All of the above are correct.
Hint
11.
Which of the following is an example of a compound machine?
a.
a can opener
b.
a doorknob
c.
a screwdriver
d.
an axe
Hint
12.
How does increasing the number of threads on a screw change the mechanical advantage of a screw?
a.
The mechanical advantage of the screw decreases.
b.
It is impossible to calculate the mechanical advantage of a screw.
c.
The mechanical advantage of the screw increases.
d.
The mechanical advantage of the screw is unaffected.
Hint
13.
What is the term used for the force applied to a machine?
a.
resistance force
b.
machine force
c.
applied force
d.
effort force
Hint
14.
Suppose you must lift a 100-kg box to a table 1 m high. How does the use of an inclined plane affect the amount of work you must perform to lift the box?
a.
You can perform less work with a shorter incline plane.
b.
An inclined plane increases the amount of work you must perform.
c.
You can perform less work with a longer inclined plane.
d.
An inclined plane does not change the amount of work you must perform.
Hint
15.
What is the mechanical advantage of a lever if the effort force is 2 N and the resistance force is 8 N?
a.
5
b.
2
c.
16
d.
4
Hint
