True/False
Indicate whether the
sentence or statement is true or false.
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1. |
If
friction is negligible, the work done on a pen in raising it 25 cm is
the same whether the pen is raised along a vertical path or along a
path inclined at some angle 
to the horizontal.
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2. |
As
you walk along a horizontal floor carrying a backpack at a constant
height above the floor, the work done by gravity on the backpack is
negative.
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3. |
Extending the situation in question 2, you come to a complete stop
to talk to a friend. As you are in the process of slowing down to stop,
the work you do on the backpack is zero.
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4. |
An
eraser falls from rest from a desktop to the floor. As it falls, its
kinetic energy increases in proportion to the square of its speed, and
its gravitational potential energy decreases in proportion to the square
of the distance fallen.
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5. |
A
ball bouncing off a floor never reaches the same height from which it
was dropped (from rest). This does not refute the law of conservation
of energy because the ball and the floor do not belong to the same isolated
system.
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6. |
Thermal energy is the same as internal energy, whereas heat is
the transfer of energy from a warmer object to a cooler one.
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7. |
In
a horizontal mass-spring system undergoing SHM, the maximum speed of
the mass occurs when the elastic potential energy is at a minimum.
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8. |
In
a vertical mass-spring system undergoing SHM, the maximum speed of the
mass occurs when the elastic potential energy is at a minimum.
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9. |
A
long damping time would be appropriate for a bathroom scale, but inappropriate
for a child’s “jolly-jumper” toy.
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Multiple Choice
Identify
the letter of the choice that best completes the statement or answers
the question.
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For questions 10 to 15, choose the graph in Figure 1 that
best represents the relationship between the described variables.
Figure 1
The first variable in questions
10 to 15 corresponds to the y-variable on one of these graphs;
the
second variable corresponds to the x-variable.
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10. |
The
y-variable is the work done by a spring; x is the spring’s
stretch.
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11. |
The
y-variable is the kinetic energy of an object; x is the
object’s speed.
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12. |
The
y-variable is the period of vibration of an object undergoing
SHM; x is the frequency of vibration.
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13. |
The
y-variable is the frequency of vibration of an object undergoing
SHM in a mass-spring system; x is the force constant of the spring.
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14. |
The
y-variable is the period squared of an object undergoing SHM
in a mass-spring system; x is the force constant of the spring.
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15. |
The
y-variable is the period squared of an object undergoing SHM
in a mass-spring system; x is the reciprocal of the force constant
of the spring.
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Figure 2
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16. |
A
child pulls a sleigh up the incline in Figure 2. The work done
by gravity on the sleigh during this motion is
a. |
mgL
cos  |
b. |
mgL sin  |
c. |
 mgL cos  |
d. |
 mgL sin  |
e. |
none
of these |
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