ame: ________________________
Exam 3--PHYS 201--F11--Chapters 10, 11, 15, & 13
Multiple Choice
Identify the choice that best completes the statement or answers the question.
____
1. When a car travels around a curve, what force provides the centripetal force?
a.
____
____
____
the frictional force between the tires and c. the normal force of the road
road
b. the force provided by the engine
d. the weight of the car
2. 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. twice Kaisa’s
b. one-quarter of Kaisa’s
c. same as Kaisa’s
3. How many revolutions is 600 degrees?
d.
e.
four times Kaisa’s
one-half of Kaisa’s
a. 2.4 rev
c. 1.7 rev
b. 3800 rev
d. 96 rev
4. 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.
b.
c.
3
θ
4
2θ
1
θ
2
d.
e.
1
1
θ
4
4θ
____
5. 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.
speed because there is no torque acting
on this
b. the buckets’ angular speed will decrease d.
because their moment of inertia is
increasing
6. Which of these are the basic SI units for torque?
the buckets’ moment of inertia will
increase, causing the buckets angular
momentum to increase
None of these are true
a.
kg
m
s
c.
m
b.
kg
m
s2
d.
kg
m2
s2
7. 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. at the pivot point
c. closer to the pivot point
b. on the same side as your nephew
d. on the seat.
8. 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
9. Bernoulli’s equation is based on which of these laws:
a.
b.
conservation of charge
conservation of momentum
c.
d.
2
conservation of matter
conservation of energy
____ 10. 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. (a)
c. (c)
b. (b)
____ 11. The presence of dark matter was inferred by Vera Rubin by observing
a. the mass of muons
c. the rotation rates of galaxies
b. the spin of electrons
d. gamma rays from black holes
____ 12. Consider this manometer. Which statement best describes the relationship between P and P 0?
a.
b.
P>P0
P=P0
c.
d.
3
P<P0
it depends on the density of the material
in the manometer
____ 13. Consider these plots of displacement versus time for an object in simple harmonic motion. How do their
periods compare?
a.
period of Object A is larger than the
c. both have the same period
period of Object B
b. period of Object B is larger than the
d. cannot tell from these graphs
period of Object A
____ 14. Consider this graphical representation of simple harmonic motion. When a particle is at point A, its position
and velocity are...
a.
b.
position and velocity are both negative
position is negative and velocity is
positive
c.
d.
4
position and velocity are both positive
position is positive and velocity is
negative
____ 15. If the frequency of periodic motion increases, how is the period affected?
a.
b.
it decreases
it increases
c.
d.
5
it remains the same
it depends on other factors
Problem
16. (15 pts) Derive the moment of inertia for a rod of mass M and length b that rotates about an axis through the
center of the rod, as in this figure:
.
6
17. (20 pts) A solid disk has a mass of 120 kg and a radius of 5 m; it is initially at rest. A small wheel turns the
disk by applying a force of ä
F = (−7.2i8 + 9.6j8) . The force is applied at a coordinate of (3m, 4m), as shown
in this figure.
a) What is the net torque, in vector notation, on the wheel?
b) What is the angular acceleration of the large wheel?
c) After t=12 seconds, what is the angular velocity of the large wheel?
d) If the radius of the smaller wheel is 0.8 m, what is the linear velocity, at t=12 s, of a point on the outer rim
of the smaller wheel?
(continue on next page if necessary)
7
.
8
18. (10 pts) A garage lift has a 53-cm-diameter piston supporting the load. Compressed air with a maximum
pressure of 200 kPa is applied to a small piston at the other end of the hydraulic system. What is the
maximum mass the lift can support?
.
9
19. (15 pts) (a)What is the position function (ie. x(t)) for a particle that has a period of 2.3 seconds, an angular
frequency of 3.4 s-1, and a maximum velocity occurring at t=1.2 seconds?
(b)What is the acceleration at t=3.5 seconds?
.
10
20. (10 pts) A boat floats in water. Two-thirds of its volume is submerged in the water. Its total volume is 3 m 3.
What is the mass of the boat?
.
11
ID: A
Exam 3--PHYS 201--F11--Chapters 10, 11, 15, & 13
Answer Section
MULTIPLE CHOICE
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
A
C
C
E
B
D
C
A
D
A
C
C
A
D
A
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
PROBLEM
16. ANS:
.
PTS: 1
17. ANS:
.
PTS: 1
18. ANS:
.
PTS: 1
19. ANS:
.
PTS: 1
20. ANS:
.
PTS: 1
1