Energy and Its Conservation
Practice Test
1.
In Figure 8-2, if the radius of the CD is 6.0 cm and the angular velocity is 5.0 rad/s, what is the linear displacement of a point on the edge in 2.0 s?
a.
60 m
b.
3.8 m
c.
0.30 m
d.
0.60 m
Hint
2.
The product of the force and the lever arm is called __________.
a.
torque
b.
equilibrium
c.
power
d.
range
Hint
3.
A sled of mass 40.0 kg is pulled along flat, snow-covered ground. The static friction coefficient is 0.28, and the kinetic friction coefficient is 0.08. What force is needed to keep the sled moving at a constant velocity?
a.
3900 N
b.
31 N
c.
3.2 N
d.
310 N
Hint
4.
The equation for calculating work when there is an angle between force and displacement is __________.
a.
W
=
Fd
b.
W
=
F
/
m
c.
W
=
F
Δ
KE
d.
W
=
Fd
cos
θ
Hint
5.
In Figure 8-2, if the radius of the CD is 6.0 cm and the angular velocity is 5.0 rad/s, what is its angular displacement in 2.0 s?
a.
0.60 rad
b.
6.0×10
1
rad
c.
1.7 rad
d.
1.0×10
1
rad
Hint
6.
A sled of mass 40.0 kg is pulled along flat, snow-covered ground. The static friction coefficient is 0.28, and the kinetic friction coefficient is 0.08. What force will be needed to start the sled moving?
a.
31 N
b.
392 N
c.
110 N
d.
147 N
Hint
7.
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.
1.8×10
4
J
c.
3.7×10
4
J
d.
-5.5×10
4
J
Hint
8.
The __________ of a machine is defined as the ratio of output work to input work.
a.
IMA
b.
efficiency
c.
mechanical advantage
d.
reliability
Hint
9.
The centripetal acceleration is given by:
a.
a
c
=
rω
2
b.
a
c
=
ω
2
/
r
c.
a
c
=
r
/
ω
d.
a
c
=
rω
Hint
10.
The energy of an object resulting from motion is __________ energy.
a.
mechanical
b.
thermal
c.
potential
d.
kinetic
Hint
11.
In Figure 9-4b, in which position does the diver have the largest moment of inertia?
a.
The third
b.
The fourth
c.
The last
d.
The second
Hint
12.
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
2
J
b.
-7.06×10
3
J
c.
-7.06×10
2
J
d.
7.06×10
3
J
Hint
13.
The ratio of resistance force to effort force is called the __________.
a.
efficiency
b.
power
c.
torque
d.
mechanical advantage
Hint
14.
When the net external force on a closed system is zero, it is described as __________.
a.
a normal system
b.
motionless
c.
an isolated system
d.
non-accelerating
Hint
15.
A collision in which kinetic energy decreases is called a(n) __________.
a.
energy conservation
b.
mechanical collision
c.
inelastic collision
d.
elastic collision
Hint
16.
The quantity of momentum used with objects rotating about a fixed axis is called __________.
a.
torque
b.
angular momentum
c.
uniform circular motion
d.
centripetal acceleration
Hint
17.
You lift a 2.73-kg textbook from the floor to a shelf 1.75 m above the floor. What is the book's gravitational potential energy relative to the floor?
a.
14.3 J
b.
-46.8 J
c.
46.8 J
d.
93.1 J
Hint
18.
Before a collision, a 35-kg object is moving at +10.0 m/s. Find the impulse that acted on the object if, after the collision, it moves at +8.0 m/s.
a.
-7.0×10
1
kg·m/s
b.
-2.8×10
2
kg·m/s
c.
-7.0×10
2
kg·m/s
d.
7.0×10
1
kg·m/s
Hint
19.
In Figure 8-5, if
m
1
= 1.0 g,
m
2
= 5.0 g, and
r
1
= 6.0 cm, what is
r
2
?
a.
0.83 cm
b.
1.2 cm
c.
0.83 m
d.
1.2 m
Hint
20.
What happens to an object when its velocity and angular velocity are zero or constant?
a.
It's in rotational equilbrium.
b.
It's in static equilibrium.
c.
It accelerates.
d.
It's in translational equilibrium.
Hint
