Energy, Work, and Simple Machines
Practice Test
1.
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.
4.0 m/s
c.
5.3 m/s
d.
8.25 m/s
Hint
2.
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 perpendicular to the lever arm.
b.
The force is applied parallel to the lever arm.
c.
The force is applied at the axis of rotation.
d.
The force is applied perpendicular to the axis of rotation.
Hint
3.
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.
0.60 m
b.
0.30 m
c.
60 m
d.
3.8 m
Hint
4.
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.
6.83 m/s
b.
8.66 m/s
c.
2.50 m/s
d.
5.00 m/s
Hint
5.
A carnival ride has a 3.0-m radius and rotates once every 1.7 s. What is the speed of the rider?
a.
5 m/s
b.
11 m/s
c.
3.4 m/s
d.
9.4 m/s
Hint
6.
Any moving object that moves through the air only under the force of gravity (after initial thrust) is a(n) __________.
a.
satellite
b.
projectile
c.
free floater
d.
vector
Hint
7.
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 m
c.
1.2 cm
d.
0.83 m
Hint
8.
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 step upwards on an upward-moving escalator.
c.
You slide to the right on the seat of a forward-moving bus.
d.
You jump up in an elevator that is going down.
Hint
9.
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.
15.3 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.
18.0 m/s relative to the water
Hint
10.
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.
3.0 m/s
2
b.
33 m/s
2
c.
22 m/s
2
d.
4.5 m/s
2
Hint
11.
A mass that rotates around its own axis is a(n) __________.
a.
orbiter
b.
satellite
c.
projectile
d.
rigid rotating object
Hint
12.
The product of mass and velocity of a moving object is defined as its __________.
a.
normal force
b.
net force
c.
impulse
d.
linear momentum
Hint
13.
The __________ of an object is the point on the object that moves in the same way that a point particle would move.
a.
axis
b.
center of mass
c.
torque
d.
orbit
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.
217 J
b.
38.4 J
c.
376 J
d.
123 J
Hint
15.
A projectile's path through space is called its __________.
a.
trajectory
b.
period
c.
flight plan
d.
range
Hint
16.
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.
25.5 J
b.
12.8 J
c.
9.10 J
d.
47.6 J
Hint
17.
The ratio of resistance force to effort force is called the __________.
a.
torque
b.
mechanical advantage
c.
efficiency
d.
power
Hint
18.
The force exerted by a machine is called the __________.
a.
mechanical advantage
b.
resistance force
c.
effort force
d.
mechanical force
Hint
19.
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
20.
An object is in __________ when the net force exerted on it is zero.
a.
rotational equilibrium
b.
translational equilibrium
c.
equilibrium
d.
static equilibrium
Hint
