Momentum and Its Conservation
Practice Test
1.
The product of the average force and the time interval over which it acts is the __________.
a.
linear momentum
b.
acceleration
c.
velocity
d.
impulse
Hint
2.
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.
12.0 m/s relative to the water
b.
15.3 m/s relative to the water
c.
18.0 m/s relative to the water
d.
9.0 m/s relative to the water
Hint
3.
Which of the following situations is physically the most like that depicted in Figure 6-9a?
a.
You step upwards on an upward-moving escalator.
b.
You jump up in an elevator that is going down.
c.
You walk toward the rear of a forward-moving train.
d.
You slide to the right on the seat of a forward-moving bus.
Hint
4.
Two freight cars, each with a mass of 2.5×10
4
kg collide. One was initially moving at 3.7 m/s; the other was at rest. They stick together. What is their final speed?
a.
0.54 m/s
b.
3.7 m/s
c.
1.9 m/s
d.
2.4 m/s
Hint
5.
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.
33 N, inward
b.
22 N, outward
c.
22 N, inward
d.
33 N, outward
Hint
6.
FΔt = mΔv
is the equation for __________.
a.
net force
b.
angular momentum
c.
impulse-momentum
d.
linear momentum
Hint
7.
A stone is thrown horizontally at 20 m/s from the top of a cliff 63 m high. How fast is it moving the instant before it hits the ground?
a.
29 m/s
b.
40 m/s
c.
33 m/s
d.
38 m/s
Hint
8.
Two 1.00-kg masses have their centers 1.00 m apart. What is the force of attraction between them?
a.
6.67×10
11
N
b.
9.7×10
-8
N
c.
1.33×10
-10
N
d.
6.67×10
-11
N
Hint
9.
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.
6.0×10
1
rad
b.
1.7 rad
c.
1.0×10
1
rad
d.
0.60 rad
Hint
10.
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
2
c.
7.61 × 10
3
m/s
d.
7.68 × 10
3
m/s
2
Hint
11.
When the net external force on a closed system is zero, it is described as __________.
a.
non-accelerating
b.
motionless
c.
a normal system
d.
an isolated system
Hint
12.
In Newton's equation,
F
=
Gm
1
m
2
/
r
2
,
r
is __________.
a.
a universal constant
b.
the distance between a planet and the Sun
c.
the distance between the centers of the masses
d.
the difference in the two masses
Hint
13.
If an object moves in a circle at steady speed it is in __________.
a.
torque
b.
equilibrium
c.
uniform circular motion
d.
projectile motion
Hint
14.
Newton's laws are valid only __________.
a.
in rotating frames
b.
on Earth
c.
in vacuum
d.
in nonaccelerated or inertial frames
Hint
15.
If you weigh 500.0 N on Earth's surface, how much would you weigh on the planet Jupiter? Jupiter has a mass of 1.90×10
27
kg and a radius of 71.5×10
6
m.
a.
126 N
b.
1270 N
c.
1.26 N
d.
1.24×10
4
N
Hint
16.
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.
45 m
b.
135 m
c.
225 m
d.
15 m
Hint
17.
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 cm
b.
1.2 m
c.
0.83 cm
d.
0.83 m
Hint
18.
In Figure 8-3, why does applying a force as in the picture at the top left result in no effect?
a.
The force is applied at the axis of rotation.
b.
The force is applied parallel to the lever arm.
c.
The force is applied perpendicular to the lever arm.
d.
The force is applied perpendicular to the axis of rotation.
Hint
19.
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.
3.8 m
b.
60 m
c.
0.60 m
d.
0.30 m
Hint
20.
An object is in __________ when the net torque exerted on it is zero.
a.
translational equilibrium
b.
rotational equilibrium
c.
static equilibrium
d.
equilibrium
Hint
