Thermal Energy
Practice Test
1.
In Figure 8-3, if the door is 0.90 m wide and you exert a force of 2.0 N as in the picture on the top right, what is the magnitude of the resulting torque on the door?
a.
0.40 N·m
b.
0.45 N·m
c.
1.8 N·m
d.
2.9 N·m
Hint
2.
The product of the force and the lever arm is called __________.
a.
range
b.
equilibrium
c.
torque
d.
power
Hint
3.
Which has the highest entropy?
a.
an ice cube
b.
a stack of books
c.
a diamond
d.
a fire
Hint
4.
Water boils at 100° on the __________ temperature scale.
a.
Celsius
b.
Kelvin
c.
Fahrenheit
d.
Molecular
Hint
5.
A 75-kg rock climber first climbs 25 m to the top of a quarry, then descends 75 m from the top to the bottom of the quarry. If the initial height is the reference level, what is the potential energy at the bottom?
a.
3.7×10
4
J
b.
-3.7×10
4
J
c.
-5.5×10
4
J
d.
1.8×10
4
J
Hint
6.
In Figure 9-4b, in which position does the diver have the smallest moment of inertia?
a.
The last
b.
The first
c.
The fourth
d.
The second
Hint
7.
A bike rider approaches a hill at a speed of 3.5 m/s. The mass of the bike and rider together is 77 kg. The rider coasts up the hill. Assuming that there is no friction, at what height will the bike come to rest?
a.
1.6 m
b.
0.62 m
c.
3.7 m
d.
4.1 m
Hint
8.
Friction that you feel when you rub your hands together was changed from __________ to heat.
a.
kinetic energy
b.
nuclear energy
c.
thermal energy
d.
sound energy
Hint
9.
The velocity of a 975-kg car is changed from 12.0 m/s to 27.0 m/s in 15.0 s by an external, constant force. What is the magnitude of the force?
a.
1.46×10
4
N
b.
975 kg·m/s
c.
9.75×10
2
N
d.
9.75×10
3
N
Hint
10.
In Figure 11-5, if the mass of an orange is about 0.6 kg, about how much more gravitational potential energy does the topmost orange have than the one in the juggler's left hand?
a.
6 J
b.
0.6 J
c.
60 J
d.
600 J
Hint
11.
An object is in __________ when the net force exerted on it is zero.
a.
rotational equilibrium
b.
static equilibrium
c.
translational equilibrium
d.
equilibrium
Hint
12.
The __________ of an object is the point on the object that moves in the same way that a point particle would move.
a.
orbit
b.
torque
c.
axis
d.
center of mass
Hint
13.
A 2.00-kg ball, A, is moving at a speed of 5.00 m/s. It collides with a stationary ball, B, of the same mass. After the collision, A moves off in a direction 30.0° to the left of its original direction. Ball B moves off in a direction 90.0° to the right of ball A's final direction. How fast is ball B moving after the collision?
a.
8.66 m/s
b.
2.50 m/s
c.
6.83 m/s
d.
5.00 m/s
Hint
14.
A student lifts a box of books that weighs 215 N. The box is lifted 1.75 m. How much work does the student do on the box?
a.
376 J
b.
38.4 J
c.
123 J
d.
217 J
Hint
15.
The ratio of resistance force to effort force is called the __________.
a.
mechanical advantage
b.
torque
c.
power
d.
efficiency
Hint
16.
The Sun warms us by __________.
a.
radiation
b.
conduction
c.
convection
d.
induction
Hint
17.
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.
65 m
c.
2.0 m
d.
1.5 m
Hint
18.
A large chunk of ice with mass 12.0 kg falls from a roof 6.00 m above the ground. Ignoring air resistance, what is the kinetic energy of the ice when it reaches the ground?
a.
-7.06×10
3
J
b.
-7.06×10
2
J
c.
7.06×10
3
J
d.
7.06×10
2
J
Hint
19.
In Figure 9-6, if
v
C
is 1 m/s,
v
D
is 7 m/s, and the mass of each ball is 2 kg, how would the magnitudes of the forces exerted by each ball on the other during the collision compare?
a.
The magnitude of the force of C on D would be greater than the magnitude of the force of D on C.
b.
The magnitude of the force of D on C would be greater than the magnitude of the force of C on D.
c.
They do not exert forces on each other.
d.
The magnitudes of the forces would be equal.
Hint
20.
A 16.8-kg boy is riding in a 4.50-kg wagon. A 14.0-kg girl pushes the wagon and exerts a constant force of 2.60 N over a distance of 3.50 m. What is the change in energy of the boy and the wagon?
a.
9.10 J
b.
47.6 J
c.
25.5 J
d.
12.8 J
Hint
