Section 10.1
Energy and Work
Practice Test
1.
The energy of an object resulting from motion is __________ energy.
a.
kinetic
b.
potential
c.
thermal
d.
mechanical
Hint
2.
A steel ball with mass 5.0 kg is at rest on a smooth, level surface. A constant force acts on it through a distance of 10.0 m causing it to roll at 25 m/s. What is the magnitude of the force?
a.
1.6×10
2
N
b.
6.3 N
c.
4.9 N
d.
1.6×10
3
N
Hint
3.
A joule is __________.
a.
1 N·s
b.
1 N·m
c.
1
F
r
/
F
e
d.
1 N·m/s
Hint
4.
A forklift raises a box 2.5 m doing 8.7 kJ of work on it. What is the mass of the box?
a.
7.2×10
2
kg
b.
3.6×10
3
kg
c.
3.5×10
3
kg
d.
3.6×10
2
kg
Hint
5.
A student lifts a box of books that weighs 215 N. The box is lifted 1.75 m. What is the change in energy of the box?
a.
376 J
b.
123 J
c.
38.4 J
d.
225 J
Hint
6.
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. How much work does the girl do pushing the wagon?
a.
0.26 J
b.
9.10 J
c.
127 J
d.
66.4 J
Hint
7.
A rifle can shoot a 4.20-g bullet at a speed of 965 m/s. What is the kinetic energy of the bullet as it leaves the rifle?
a.
2.03×10
3
J
b.
1.96×10
3
J
c.
1.96×10
6
J
d.
2.03 J
Hint
8.
An electric motor lifts an elevator 14.0 m in 22.5 s by exerting an upward force of 1.75×10
4
N. What power does the motor produce in kilowatts?
a.
245 kW
b.
2.45×10
4
kW
c.
1.09×10
4
kW
d.
10.9 kW
Hint
9.
The unit for kinetic energy is the __________.
a.
joule
b.
volt
c.
ampere
d.
watt
Hint
10.
A rope is used to pull a metal box 12.0 m across the floor with a force of 456 N. The rope is held at an angle of 52.0° with the floor. How much work does the puller do?
a.
3.37×10
2
J
b.
5.47×10
3
J
c.
3.37×10
3
J
d.
4.31×10
3
J
Hint
11.
If the boy in Figure 10-3 pushes on the car while it travels a horizontal distance of 1.1 m, how much work does he do?
a.
140 J
b.
120 J
c.
64 J
d.
58 J
Hint
12.
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.
12.8 J
b.
47.6 J
c.
9.10 J
d.
25.5 J
Hint
13.
In Figure 10-1, if the force exerted on a 3.0-kg backpack that is initally at rest is 20.0 N and the distance it acts over is 0.25 m, what is the final speed of the backpack?
a.
2.8 m/s
b.
3.3 m/s
c.
5.0 m/s
d.
1.8 m/s
Hint
14.
The work-energy theorem states that __________.
a.
when work is done on an object, a change in kinetic energy results.
b.
effort is required to resist a change in the energy of a system
c.
when a machine works at 100 percent efficiency, the energy of the system remains constant
d.
when work is done at a rate of one joule per second, the power produced is one watt
Hint
15.
If you exert a force on an object in the direction opposite to its motion, the kinetic energy of the object __________.
a.
is zero
b.
decreases
c.
increases
d.
remains constant
Hint
16.
In Figure 10-1, if the force exerted on the backpack is 20.0 N and the distance it acts over is 0.25 m, what is the change in kinetic energy of the backpack?
a.
2.5 J
b.
8.0×10
1
J
c.
5.0 J
d.
4.0×10
1
J
Hint
17.
A 1200.0-kg car speeds up from 16.0 m/s to 20.0 m/s. What were its initial and final energies?
a.
initial 3.07×10
5
J, final 4.80×10
5
J
b.
initial 4.80×10
5
J, final 3.07×10
5
J
c.
initial 1.54×10
5
J, final 2.40×10
5
J
d.
initial 2.40×10
5
J, final 1.54×10
5
J
Hint
18.
Energy is defined as __________.
a.
the effort required to perform work
b.
motion
c.
power
d.
the ability of an object to produce change in the environment or itself
Hint
19.
A hydrolic lift raises a 1.14×10
3
-kg car a distance of 2.4 m. If the car is lifted in 47 s, how much power does the lift produce?
a.
58.2 W
b.
290 W
c.
570 W
d.
570 kW
Hint
20.
A sailor pulls a boat 15.0 m along a dock using a rope that makes a 45.0° angle with the horizontal. How much work does the sailor do on the boat if he exerts a force of 185 N on the rope?
a.
2.78×10
3
J
b.
1.96×10
2
J
c.
1.59×10
3
J
d.
1.96×10
3
J
Hint
21.
How much work does the force of gravity do on a 5.45-kg bowling ball that falls a distance of 0.755 m?
a.
71.2 J
b.
4.11 J
c.
40.3 J
d.
262 J
Hint
22.
An airplane passenger carries a 300.0-N suitcase up the stairs, a displacement of 5.50 m vertically and 3.75 m horizontally. How much work does the passenger do?
a.
1.13×10
3
J
b.
2.78×10
3
J
c.
1.65×10
3
J
d.
1.65×10
2
J
Hint
23.
A 1200.0-kg car speeds up from 16.0 m/s to 20.0 m/s. How much work was done on the car to increase its speed?
a.
3.1×10
5
J
b.
8.6×10
5
J
c.
8.6×10
4
J
d.
9.6×10
3
J
Hint
24.
One __________ is one joule of energy transferred in one second.
a.
calorie
b.
newton
c.
volt
d.
watt
Hint
25.
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.
38.4 J
b.
376 J
c.
217 J
d.
123 J
Hint
26.
The equation for work is __________.
a.
W
=
F
/
m
b.
W
=
F
Δ
KE
c.
W
=
ma
d.
W
=
Fd
Hint
27.
How much work does the force of gravity do when a 50.0-N object falls a distance of 10.0 m?
a.
125 J
b.
51.0 J
c.
98.0 J
d.
5.00×10
2
J
Hint
28.
The equation for calculating work when there is an angle between force and displacement is __________.
a.
W
=
Fd
cos
θ
b.
W
=
F
/
m
c.
W
=
Fd
d.
W
=
F
Δ
KE
Hint
29.
Which of the following has the greatest kinetic energy, a 35.0-g bullet traveling at 1.20×10
3
m/s, a 35.0-kg cheetah running at 30 m/s, an 875-kg car traveling at 5 m/s, or a 148-g pitched baseball moving at 45 m/s?
a.
cheetah
b.
bullet
c.
car
d.
baseball
Hint
30.
__________ is the rate of doing work.
a.
Power
b.
Energy
c.
Effort
d.
Force
Hint
