ame: ________________________
Exam 3--PHYS 101--Fall 2010
Multiple Choice
Identify the choice that best completes the statement or answers the question.
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1. A tire placed on a balancing machine in a service station starts from rest and turns through
3.2 revolutions in 2.0 s before reaching its final angular speed. Calculate its angular
acceleration in rad/s 2.
a.
b.
____
6.4 rad/s2
10.1 rad/s2
c.
d.
5.0 rad/s2
1.6 rad/s2
2. A tire 1.0 m in diameter is placed on a balancing machine, where it is spun so that its tread
is moving at a constant speed of 20.0 m/s. A small stone is stuck in the tread of the tire.
What is the acceleration of the stone as the tire is being balanced?
____
a. 800 m/s2
c. 10 m/s2
2
b. 20 m/s
d. 400 m/s2
3. Chad & Kaisa are on a spinning merry-go-round. Chad is on the outside edge and Kaisa is near the center of
the merry-go-round. Which has the larger centripetal acceleration?
a.
b.
Chad
Kaisa
c.
d.
1
both the same
not enough information
____
4. A certain light truck can go around a flat curve having a radius of 120 m with a maximum
speed of 25.0 m/s. With what maximum speed can it go around a curve having a radius of
75.0 m?
a.
b.
____
20 m/s
390 m/s
c.
d.
15 m/s
30 m/s
5. This figure shows a truck on a banked curve and all the force vectors acting on it. A driver
can safely drive at a higher speed on a banked curve rather than on a flat curve. Which of
these reasons is the correct explanation of why this is possible?
a.
b.
c.
d.
The normal force for the car on the banked curve is less than on a flat curve
The weight of the car is greater on the banked curve than on a flat curve
On a banked curve, a component of the weight acts down the slope, thus increasing the
centripetal force.
The static frictional force for the tires on the banked curve is greater than on a flat curve
2
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____
____
6. An object is travelling in a counterclockwise circular path. At the point shown, the string holding the ball in
the circular path is cut. What is the path that the ball follows after the string is cut?
a. a
c. c
b. b
d. d
7. The speedometer on my bicycle measures the angular speed and converts it to linear speed based on the
radius of the wheels, which I input. Suppose that I input a radius that is smaller than the actual radius of the
wheel. Which of these statements will be true?
a. speedometer reads a higher speed than the true linear speed
b. speedometer still reads the true linear speed
c. speedometer reads a lower speed than the true linear speed
8. A roller derby lady holds onto a rope that is tied to a post. She skates around the post, and the rope gets
shorter and shorter. If her angular speed remains constant, what happens to the tension in the rope?
a.
b.
it increases
it stays the same
c.
d.
3
it decreases
not enough information to tell
____
9. Which of these arrangements provides the greatest torque?
a. a
c. c
b. b
d. d
____ 10. Chad stands on a 5 m long board, 4 meters from the pivot point as shown in this figure. He has a mass of 75
kg. Kaisa has a mass of 60 kg. Where can she stand to balance the board?
a.
b.
1 m to the left of the pivot point
Next to Chad
c.
d.
4
0.5 m to the left of the pivot point
she cannot balance the board
____ 11. Calculate the net torque acting on this rod about an axis through the point C and perpendicular to the page:
a. 35 Nm, CCW
d. 10 Nm, CCW
b. 45 Nm, CW
e. 14 Nm, CW
c. 22 Nm, CCW
____ 12. This figure shows 4 balls, each with a mass of 1.0 kg, attached with rigid, massless rods on the corners of a
square. Each rod is 1.0 meter in length. The rotation axis is at a point equidistant between the two sides of
the square. What is the moment of inertia of the configuration?
a.
b.
2.0 kg m2
0.5 kg m2
c.
d.
5
0.25 kg m2
1.0 kg m2
____ 13. A merry-go-round has a mass of 100 kg and a radius of 1m. It is spinning at 2 rev/s. A kid with a mass of 50
kg jumps onto the outer rim of the merry-go-round. What is the angular velocity of the merry-go-round after
the kid jumps aboard?
a. 4 rev/s
c. 0.5 rev/s
b. 2 rev/s
d. 1 rev/s
____ 14. A horizontal 100.0 kg merry-go-round of radius 1.0 m is started from rest by a constant horizontal force of
50.0 N applied tangentially to the merry-go-round. Find the kinetic energy of the merry-go-round after 3.00 s.
(Assume it is a solid cylinder.)
a. 5000 J
c. 10,000 J
b. 900 J
d. 230 J
____ 15. While swimming near the bottom of a pool, you let out a small bubble of air. As the bubble rises toward the
surface, its diameter increases. What happens to the pressure of the air in the bubble as it rises to the
surface?
a.
b.
decreases
increases
c.
6
remains the same
____ 16. This figure shows four identical C-shaped objects. Each rotates around the axis drawn with the thin black
line. Rank the four objects from least moment of inertia to the greatest moment of inertia.
a. b>c=d>a
c. d=c>b>a
b. a=b=c=d
d. d>b>c>a
____ 17. In a mercury barometer at atmospheric pressure, the height of the column of mercury in a glass tube is 760
mm. If the mercury in the barometer is replaced with water, what will be the height of the column?
a.
b.
<760 mm
=760 mm
c.
7
>760 mm
____ 18. A block of unknown density is floating in a fluid such as in this figure. Which of these statements about the
density of the block is true?
a.
the block is more dense than the fluid
c.
the block has the same density than the
fluid
b. the block is less dense than the fluid
d. the block has more mass than the fluid
____ 19. Blood enters a clogged artery as in this figure. What happens to the pressure of the blood inside the clogged
portion of the artery?
a. the pressure increases
c. the pressure remains the same
b. the pressure decreases
d. not enough information
____ 20. A block has a mass of 1 kg and floats halfway submerged in water. What is the density of the object?
a.
b.
c.
2000 kg/m3
250 kg/m3
1000 kg/m3
d.
e.
8
500 kg/m3
not enough information
____ 21. This figure shows a manometer, which is filled with mercury. The pressure of the atmosphere (=1 atm) acts
on the left side of the manometer. The temperature of the methane gas inside the bulb is 37°C. What is the
pressure of the methane? (The density of mercury is 13,600 kg/m 3.)
a. 107,000 Pa
c. 100,000 Pa
b. 93,000 Pa
d. 570,000 Pa
____ 22. The following figure shows the top half of a pipe carrying water. The standpipes along the top are used to
measure the pressure. Where is the pressure greatest?
a. A
c. C
b. B
d. all the same
____ 23. For the previous figure, which of the following statements best describes the shape of the bottom portion of
the pipe, which isn’t shown in the figure?
a.
the pipe narrows from left to right
c.
b.
the pipe gets wider from left to right
d.
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the pipe has a constant cross-sectional
area from left to right
none of these
____ 24. This figure shows a hydraulic lift. The force F 1 has a magnitude of 100 N, and the area A1 is 0.01 m2. If the
area A2 is 1.0 m2, what is the weight of the truck?
a. 100,000 N
c. 1000 N
b. 1,000,000 N
d. 10,000 N
____ 25. The answer to this question is “A.” Bubble “A” on your scantron.
a. A
c. C
b. B
d. D
10
ID: A
Exam 3--PHYS 101--Fall 2010
Answer Section
MULTIPLE CHOICE
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