Momentum and Its Conservation
Practice Test
1.
In Figure 6-7, if the mass of the hammer is 7.26 kg, its center is 0.50 m from the thrower, and it is moving at a speed of 1.5 m/s, what is the force of the chain on the thrower's hands?
a.
22 N, outward
b.
22 N, inward
c.
33 N, outward
d.
33 N, inward
Hint
2.
The quantity of momentum used with objects rotating about a fixed axis is called __________.
a.
angular momentum
b.
uniform circular motion
c.
centripetal acceleration
d.
torque
Hint
3.
A satellite orbits Earth 375 km above its surface. What is its speed in orbit?
a.
7.68 × 10
3
m/s
b.
7.61 × 10
3
m/s
c.
7.68 × 10
3
m/s
2
d.
7.61 × 10
3
m/s
2
Hint
4.
A satellite orbits Earth 5.00×10
2
km above its surface. What is its period?
a.
15.7 h
b.
1.43 h
c.
94.6 h
d.
1.58 h
Hint
5.
Which of the following situations is physically the most like that depicted in Figure 6-9a?
a.
You walk toward the rear of a forward-moving train.
b.
You slide to the right on the seat of a forward-moving bus.
c.
You jump up in an elevator that is going down.
d.
You step upwards on an upward-moving escalator.
Hint
6.
Two balls have their centers 3.0 m apart. One ball has a mass of 2.7 kg. The other has a mass of 4.5 kg. What is the gravitational force between them? Assume
G
= 6.67×10
-11
N·m
2
/kg
2
.
a.
9.0×10
-11
N
b.
2.7×10
-10
N
c.
9.0×10
-10
N
d.
1.3×10
-11
N
Hint
7.
Which of the following equations represents Newton's law of universal gravitation?
a.
T
3
= (4
π
2
/
Gm
s
)
r
2
b.
G
=
Fm
1
m
2
/
r
2
c.
F
=
Gm
1
m
2
/
r
2
d.
T
2
= (4
π
2
/
Gm
s
)
r
3
Hint
8.
A stone is thrown horizontally at 20.0 m/s from the top of a cliff 63 m high. How far from the base of the cliff does the stone hit the ground?
a.
42 m
b.
66 m
c.
13 m
d.
72 m
Hint
9.
Two campers dock a canoe. One camper has a mass of 100.0 kg and moves forward at 3.0 m/s as he leaves the canoe to step onto the dock. With what speed do the canoe and other camper move if their combined mass is 175.0 kg?
a.
1.7 m/s
b.
5.3 m/s
c.
4.0 m/s
d.
8.25 m/s
Hint
10.
You accidentally throw your car keys horizontally at 5.0 m/s from a cliff 45 m high. How far from the base of the cliff should you look for your keys?
a.
15 m
b.
45 m
c.
225 m
d.
135 m
Hint
11.
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.
1.2 m
b.
1.2 cm
c.
0.83 m
d.
0.83 cm
Hint
12.
You are riding in a boat that is traveling 15.0 m/s in still water. You move from the bow to the stern at 3.0 m/s. What is your speed relative to the water?
a.
18.0 m/s relative to the water
b.
9.0 m/s relative to the water
c.
12.0 m/s relative to the water
d.
15.3 m/s relative to the water
Hint
13.
The centripetal acceleration is given by:
a.
a
c
=
r
/
ω
b.
a
c
=
ω
2
/
r
c.
a
c
=
rω
d.
a
c
=
rω
2
Hint
14.
All the forces within a closed system are __________.
a.
internal forces
b.
angular forces
c.
due to gravity
d.
external forces
Hint
15.
An object is in __________ when the net torque exerted on it is zero.
a.
static equilibrium
b.
translational equilibrium
c.
rotational equilibrium
d.
equilibrium
Hint
16.
In Figure 6-7, if the mass of the hammer is 7.26 kg, its center is 0.50 m from the thrower, and it is moving at a speed of 1.5 m/s, what is its centripetal acceleration?
a.
33 m/s
2
b.
22 m/s
2
c.
3.0 m/s
2
d.
4.5 m/s
2
Hint
17.
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 resulting change in momentum of the car?
a.
2.19×10
5
kg[dot]m/s
b.
1.46×10
4
kg[dot]m/s
c.
7.22×10
4
kg[dot]m/s
d.
9.75×10
2
kg[dot]m/s
Hint
18.
The product of the force and the lever arm is called __________.
a.
equilibrium
b.
torque
c.
power
d.
range
Hint
19.
A mass that rotates around its own axis is a(n) __________.
a.
orbiter
b.
rigid rotating object
c.
satellite
d.
projectile
Hint
20.
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.
1.7 rad
b.
0.60 rad
c.
6.0×10
1
rad
d.
1.0×10
1
rad
Hint
