C. Work Take Home Quiz

**300 Points Possible ( 10 points/question)**

For Questions
#1-9, Match the unit or expression to the physical quantity.

a) friction f) mgy k) ftlb

b) J/s g) 1/2 mv^{2} l) -kx

c) dyne cm h) dimensionless m) weight

d) N m i) N/m n) ftlb/s

e) 550 ftlb/s j) 3.6 MJ

1. joule

2. kinetic energy

3. potential energy

4. conservative force

5. non-conservative force

6. spring constant

7. hp

8. Hooke's Law

9. watt

10. Two men, Joel and Jerry, push against a
wall. Jerry stops after 10 min, while
Joel is able to push for 5 min longer.
Compare the work they do.

a. Joel
does 50% more work than Jerry.

b. Jerry
does 50% more work than Joel.

c. Joel
does 75% more work than Jerry.

d. Neither
of them do any work.

11. You lift a 10-lb physics book up in the air a
distance of 1 ft, at a constant velocity of 0.5 ft/s. The work done by gravity is

a. +10
ftlb

b. -10
ftlb

c. +5 ftlb

d. -5
ftlb

e. zero

Page 2

12. The area under the curve, on a Force-position
(F-x) graph, represents

a. work.

b. kinetic
energy.

c. power.

d. efficiency.

13. Which of the graphs illustrates Hooke's Law?

a. graph
A

b. graph
B

c. graph
C

d. graph
D

Page 3

14. Which of the above graphs represent a spring
which gets less stiff the more it is stretched?

a. graph
A

b. graph
B

c. graph
C

d. graph
D

15. A 10-kg mass, hung onto a spring, causes the
spring to stretch 2.0 cm. The spring
constant is

a. 49
N/cm

b. 5.0
N/cm

c. 0.20
N/cm

d. 0.0020
N/cm

Page 4

16. A simple pendulum, consisting of a mass m and a
string, swings upward, making an angle q with the vertical. The work done
by the tension force is: (Hint: Ask
yourself this question: “Does the ‘bob’
move because of the tension in the string?”
If yes, then there is work done by the tension, if not, then the answer
is zero)

a. zero

b. mg

c. mg
cos q

d. mg
sin q

17. Matthew pulls his little sister Sarah in a sled
on a flat, icy surface (assume no friction), with a force of 60 N at an angle
of 37^{o} upward from the
horizontal. If he pulls her a distance
of 12 m, the work he does is

a. 185
J

b. 433
J

c. 575
J

d. 720
J

18. A container of water is lifted vertically 3 m,
then returned to its original position.
If the total weight is 30 N, how much work was done?

a. 45 J

b. 90 J

c. 180
J

d. No
work was done.

19. A truck weighs twice as much as a car, and is
moving at twice the speed of the car.
Which statement is true about the truck's kinetic energy (K) compared to
that of the car?

a. All
that can be said is that the truck has more K.

b. The
truck has twice the K of the car.

c. The
truck has 4 times the K of the car.

d. The
truck has 8 times the K of the car.

20. A toy rocket, weighing 10 N, blasts off from
ground level. At the exact top of its
trajectory, its energy is 140 J. To
what vertical height does it rise?

a. 1.4
m

b. 14.
m

c. 1.4
km

d. None
of the above

Page 5

21. You slam on the brakes of your car in a panic,
and skid a certain distance on a straight, level road. If you had been traveling twice as fast,
what distance would the car have skidded, under the same conditions?

a. It would have skidded 4 times farther.

b. It would have skidded twice as far.

c. It would have skidded ÚÄ times farther.

ű2

d. It is impossible to tell from the
information given.

22. On the accompanying diagram of a pendulum, at
what position is the potential energy maximum?

a. A

b. B

c. C

23. On the accompanying diagram of a pendulum, at
what position is the kinetic energy maximum?

a. A

b. B

c. C

Page 6

24. Which of the following is **not** a unit of work?

a. Kg-m/s

b. J

c. Kw-h

d. N-m

e. W-s

25. If both mass and the velocity of a ball are
each tripled, the kinetic energy is increased by a factor of:

a. 3

b. 6

c. 9

d. 18

e. 27

f. 81

26. Consider a plot of the displacement (x) vs
applied force (F) for an ideal elastic spring. The slope of the curve would
be: (Hint: When you read this question, be sure you
understand which unit is on which axis.
In other words, refer to your knowledge of _____ vs. ______ graphs. Which one is on the x-axis and which is on
the y-axis?)

a. the
spring constant

b. the
reciprocal of the spring constant

c. the
acceleration of gravity

d. the
reciprocal of the acceleration of gravity

e. none
of the above

27. The work energy theorem says

a. the
net work done is equal to the initial kinetic energy less the final energy.

b. final
kinetic energy plus the net work done is the initial kinetic energy.

c. the
net work done plus the initial kinetic energy is the final kinetic energy.

d. the
net work done plus the final kinetic energy is the initial kinetic energy.

e. the
net work done minus the initial kinetic energy is the final kinetic energy.

28. Consider the work
lab that we did in class. Is there any
difference in the amount of force it takes to pull the cart up the ramp at a constant velocity and the force it takes to just hold
the cart in place (for example: Say you
pull the cart half-way up the ramp and just let the force meter register its
readings as you hold still)

a.
yes, there is a difference. The
force is greater when you pull it than when you hold it still.

b.
yes, there is a difference. The
force is lower when you pull it than when you hold it still.

c.
No, there is no difference

29. Still consider
that work lab (Remember you were dragging an object up ramps of varying
distance, but the HEIGHT WAS ALWAYS THE SAME).
What is the only circumstance(s) under which the force of friction has NO EFFECT on the work done by the system. (Answer may be more than one letter)

a.
When you are pulling a wooden block up the ramp (which does have
friction).

b.
When you are pulling a wooden block up a frictionless ramp.

c.
When you are pulling a cart on wheels up a frictionless ramp.

d.
When you are pulling a cart on wheels up a friction ramp.

30. Again with the
work lab (will he ever stop asking questions???!! - NOPE, SORRY). What
happens to the normal force on the cart as you raise the ramp to a vertical
position.

a.
Normal force increases towards mg

b.
Normal force decreases towards 0

c.
Normal force doesn’t exist for carts on wheels.