Section 10.2
Machines
Practice Test
1.
If the machine in Figure 10-11a is ideal and an effort force of 7.0 N just lifts a 14.0 N box situated 0.75 m from the pivot, what is the distance from the pivot point to where the effort force is exerted?
a.
0.38 m
b.
1.5 m
c.
65 m
d.
2.0 m
Hint
2.
If the efficiency of the pulley system in Figure 10-11b is 95 percent, what effort force must be exerted to lift a 20.0 N box at constant velocity?
a.
21 N
b.
22 N
c.
20 N
d.
19 N
Hint
3.
The ratio of resistance force to effort force is called the __________.
a.
efficiency
b.
mechanical advantage
c.
torque
d.
power
Hint
4.
The __________ of a machine is defined as the ratio of output work to input work.
a.
reliability
b.
efficiency
c.
IMA
d.
mechanical advantage
Hint
5.
The rear wheel of a bicycle has a radius of 38.5 cm and has a gear with a radius of 4.75 cm. When the chain is pulled with a force of 175 N, the wheel rim moves 18.0 cm. The efficiency of this part of the bike is 95.0 percent. How far was the chain pulled to move the rim that amount?
a.
2.21 cm
b.
1.45 cm
c.
2.12 cm
d.
1.45×10
2
cm
Hint
6.
The force exerted by a machine is called the __________.
a.
effort force
b.
mechanical advantage
c.
resistance force
d.
mechanical force
Hint
