Section 9.1
Impulse and Momentum
Practice Test
1.
Linear momentum is the __________.
a.
product of the mass and velocity of a moving object
b.
quantity of motion used with objects rotating about a fixed axis
c.
average force and the time interval over which it acts
d.
angular momentum and torque
Hint
2.
FΔt = mΔv
is the equation for __________.
a.
impulse-momentum
b.
linear momentum
c.
angular momentum
d.
net force
Hint
3.
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.
1.46×10
4
kg[dot]m/s
b.
9.75×10
2
kg[dot]m/s
c.
2.19×10
5
kg[dot]m/s
d.
7.22×10
4
kg[dot]m/s
Hint
4.
The product of the average force and the time interval over which it acts is the __________.
a.
impulse
b.
velocity
c.
acceleration
d.
linear momentum
Hint
5.
Which one of the changes to the situation in Figure 9-2 listed below would require the airbag to exert a larger average force on the passenger?
a.
The time required to stop the passenger is lengthened.
b.
The passenger's weight is decreased.
c.
The initial speed of the passenger is decreased.
d.
The time required to stop the passenger is shortened.
Hint
6.
A constant force of 4.5 N acts on a 7.2-kg object for 10.0 s. What is the change in the object's velocity?
a.
6.3 m/s
b.
3.2 m/s
c.
1.2 m/s
d.
4.33 m/s
Hint
7.
The quantity of momentum used with objects rotating about a fixed axis is called __________.
a.
angular momentum
b.
torque
c.
uniform circular motion
d.
centripetal acceleration
Hint
8.
A 930-kg car traveling 56 km/h comes to a complete stop in 2.0 s. What is the force exerted on the car during this stop?
a.
-7.2×10
3
N
b.
7.2×10
3
N
c.
-2.5×10
4
N
d.
2.5×10
4
N
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.
9.75×10
2
N
b.
1.46×10
4
N
c.
9.75×10
3
N
d.
975 kg·m/s
Hint
10.
The product of mass and velocity of a moving object is defined as its __________.
a.
linear momentum
b.
impulse
c.
net force
d.
normal force
Hint
11.
In Figure 9-4b, in which position does the diver have the largest moment of inertia?
a.
The second
b.
The third
c.
The fourth
d.
The last
Hint
12.
Which of the following is the equation for impulse-momentum?
a.
F
Δ
t
= mΔ
v
b.
p
=
m
v
c.
F
=
m
a
d.
g
=
F
/
m
Hint
13.
If an air bag such as the one shown in Figure 9-2 changes a 6.0×10
1
kg person's speed from 40.0 m/s to 0.0 m/s, what impulse must act on the person?
a.
You cannot solve this problem without knowing the time it takes to stop the person.
b.
2400 kg m/s
c.
1.5 kg m/s
d.
0.67 kg m/s
Hint
14.
The impulse is the product of the __________.
a.
average force and the time interval over which it acts
b.
mass and velocity of a moving object
c.
average force and the distance the object travels
d.
angular momentum and torque
Hint
15.
The impulse-momentum theorem states that __________.
a.
the impulse on an object is equal to the change in momentum it causes
b.
the force on a moving object is equal to the magnitude of the impulse
c.
the impulse on an object is greater than the change in momentum it causes
d.
the impulse on an object is less than the change in momentum it causes
Hint
16.
Your sister's mass is 43.5 kg, and she is riding her 8.00-kg bicycle. What is the combined momentum of your sister and her bike if they are going 2.40 m/s?
a.
85 kg·m/s
2
b.
124 kg·m/s
2
c.
104 kg·m/s
d.
124 kg·m/s
Hint
17.
Small rockets are used to make tiny adjustments in the speed of satellites. One such rocket has a thrust of 50.0 N. If it is fired to change the velocity of a 75,000-kg spacecraft by 45 cm/s, how long should it be fired?
a.
18.8 min
b.
9.4 min
c.
22 min
d.
11 min
Hint
18.
In Figure 9-4b, in which position does the diver have the smallest moment of inertia?
a.
The first
b.
The second
c.
The fourth
d.
The last
Hint
