ame: ________________________
Exam 3--PHYS 101--F11--Chapters 7, 8, & 9
Multiple Choice
Identify the choice that best completes the statement or answers the question.
____
____
1. A 1500 kg truck must travel a maximum of 22 m/s around a curve that has a radius of 52 m. What is the
coefficient of static friction between the truck’s tires and the road?
a. 106
c. 1.2
b. 0.45
d. 0.95
2. When a car travels around a curve, what force provides the centripetal force?
a.
____
the frictional force between the tires and c. the weight of the car
road
b. the force provided by the engine
d. the normal force of the road
3. A little boy pushes his sister around on a merry-go-round. It begins at rest, and, after 12 seconds, is traveling
at 3.6 revolutions per second. How many revolutions does the merry-go-round complete in these 12 seconds?
a.
b.
40 rev
3.6 rev
c.
d.
1
11 rev
22 rev
____
____
____
____
4. A sample of blood is placed in a centrifuge of radius 0.15 m. The mass of a red
blood cell is 3.0×10-16 kg, and the magnitude of the force acting on it as it settles
out of the plasma is 4.0×10-11 N. At how many radians per second should the
centrifuge be operated?
a. 1500 rad/s
c. 20000 rad/s
b. 940 rad/s
d. 1.8×10-27 rad/s
5. Kaisa sits on the outer rim of a merry-go-round, and Chad sits midway between the rim and center. The
merry-go-round makes 1 revolution every 2 seconds. Chad’s angular velocity is ...
a. four times Kaisa’s
b. one-half of Kaisa’s
c. twice Kaisa’s
6. How many revolutions is 600 degrees?
d.
e.
one-quarter of Kaisa’s
same as Kaisa’s
a. 96 rev
c. 1.7 rev
b. 2.4 rev
d. 3800 rev
7. An object at rest begins to rotate with a constant angular acceleration. If this object rotates through an angle
θ in the time t, through what angle did it rotate in the time 2t?
a.
1
θ
4
d.
b.
2θ
e.
c.
4θ
2
1
θ
2
3
θ
4
____
8. What is the net torque acting on this bar about the point C?
____
a. 67 Nm clockwise
c. 19 Nm counterclockwise
b. 59 Nm counterclockwise
d. 12 Nm clockwise
9. A merry-go-round with a mass of 1000 kg has a radius of 2.0 m. It is started from rest by a constant
horizontal force of 50.0 N applied tangentially to the merry-go-round. What is its angular velocity after 2.00
s. (Assume it is a solid cylinder.)
a.
b.
0.05 rad/s
0.2 rad/s
c.
d.
3
100 rad/s
0.1 rad/s
____ 10. A solid metal sphere whose mass is 12.5 kg has a radius of 1.00 m. It is spinning at a rate of 2.00 rad/s.
What is the rotational kinetic energy of the sphere?
a. 25.0 J
c. 18.9 J
b. 10.0 J
d. 12.5 J
____ 11. The following figure shows a configuration of particles arranged on an equilateral triangle, whose sides are
all 4.0 m. The rotation axis is the dashed line in this figure. What is the moment of inertia for this
configuration of charges?
a.
b.
64.0 kg m2
112 kg m2
c.
d.
4
16.0 kg m2
8.00 kg m2
____ 12. Buckets are spinning horizontally on frictionless bearings. Suddenly, it starts raining. Which of these
statements is true:
a.
the buckets will spin at the same angular c. the buckets’ angular speed will decrease
speed because there is no torque acting
because their moment of inertia is
on this
increasing
d. None of these are true
b. the buckets’ moment of inertia will
increase, causing the buckets angular
momentum to increase
____ 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. 2 rev/s
c.
b. 0.5 rev/s
d.
____ 14. Which of these are the basic SI units for torque?
a.
kg
m
s2
c.
4 rev/s
1 rev/s
kg
m
s
m2
s2
____ 15. You want to see-saw with your (much smaller) 3-year old nephew. He sits on the seat of the seesaw. Where
should you sit to make this easier?
a. on the same side as your nephew
c. on the seat.
b. at the pivot point
d. closer to the pivot point
b.
m
d.
5
kg
____ 16. Two spheres have the same mass. One sphere is made of aluminum, while the other sphere is made of gold.
Both are solid. Because gold is more dense, the radius of the gold sphere is smaller than the aluminum
sphere. Which has the larger moment of inertia?
a. aluminum sphere
c. both the same
b. gold sphere
d. not enough information
____ 17. This figure shows a barometer, which is filled with mercury. The height of the column of mercury is h=1200
mm. In units of atmospheres, what is the pressure P?
a. 1.0 atm
c. 1.6 atm
b. 0.16 atm
d. 92,000 atm
____ 18. Bernoulli’s equation is based on which of these laws:
a.
b.
conservation of charge
conservation of energy
c.
d.
6
conservation of matter
conservation of momentum
____ 19. Water flows through a pipe at 3.0 m/s with a cross-sectional area of 0.5 m 2. The pipe grows wider to 1.0 m2.
What is the speed of the water in the larger pipe?
a. 6.0 m/s
c. 1.0 m/s
b. 1.5 m/s
d. 3.0 m/s
____ 20. Consider this hydraulic lift. The area of the left side (A 1) is 0.01 m2, and the area of the right side (A 2) is 1.2
m2. What force (F 1) is required to lift a car with a mass of 1000 kg?
a. 12 N
c. 82 N
b. 8.3 N
d. 9800 N
____ 21. Consider this section of pipe that narrows as it goes from left to right. An ideal fluid flows through this pipe.
Where is the pressure the highest?
a.
b.
(a)
(b)
c.
7
(c)
____ 22. The presence of dark matter was inferred by Vera Rubin by observing
a. the mass of muons
c. the spin of electrons
b. the rotation rates of galaxies
d. gamma rays from black holes
____ 23. An aluminum block has a mass of 1200 kg. What is its volume?
a. 0.023 m3
c. 2.3 m3
b. 0.44 m3
d. 3.3×106 m3
____ 24. Consider this manometer. Which statement best describes the relationship between P and P 0?
a.
b.
P>P0
P=P0
____ 25. The answer to this question is “B.”
a. A
b. B
c.
d.
P<P0
it depends on the density of the material
in the manometer
c.
d.
C
D
8
ID: A
Exam 3--PHYS 101--F11--Chapters 7, 8, & 9
Answer Section
MULTIPLE CHOICE
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