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PHY 110 Practice Final
4B
t
Consider the expression x  x o  Ae
1. (2 pts.) What are the units of A?
b) s 2
a) m
2
2
c)
, where x and xo are in meters, and t is in seconds.
m
s2
d)
s2
m
2. (2 pts.) What are the units of B?
2
2
s
1
s
a)
b) 2
c)
d) indeterminate
2
m
m
m
The units of B should be seconds, assuming the 4 has no units, but that choice is not given.
3. (4 pts.) If A = 3i + 4j and B = -8i + 6j, which of the following statement(s) is (are) true?
A)
B)
C)
D)
A is perpendicular to B.
B is twice as long as A.
A is antiparallel to B (same line, opposite direction).
A  B is in the k direction.
a) A & B only b) A & C only
c) A, B & D only
d) B, C & D only
4. (2 pts.) If the average velocity of an object in some time interval is zero, one can definitely conclude that
(choose one)
a) The object was stationary during the time interval.
b) The object's displacement was zero.
c) The acceleration of the object was constant.
d) No general conclusion can be reached.
5. (4 pts.)
acceleration.
Label the following statements True or False for 1-dimensional motion with constant
__F__ Velocity changes quadratically with time.
__F__ Velocity changes linearly with position.
__F__ The slope of the position vs. time curve is constant.
tf
_T___
 v(t)dt gives the displacement of the object during the time interval from ti to tf.
ti
6. (2 pts.) A person drops a fork on a train moving with constant velocity. Which statement is true? Circle
one. a is acceleration.
a) a fork relative to train < a fork relative to earth
b) a fork relative to train > a fork relative to earth
c) a fork relative to train = a fork relative to earth
d) The relationship of the 2 quantities depends on the direction of the velocity of the train
(uphill, downhill, etc.).
7. (2 pts.) An object traveling with constant speed in a circular path experiences (circle all that apply)
a) radial acceleration outward
b) tangential acceleration in the direction of its instantaneous velocity
c) no acceleration at all
d) none of the above
There is always centripetal acceleration (radially inward), but “constant speed” means no tangential
accleration.
8. (2 pts.) Two observers, one in a fixed reference frame, the other in a frame moving with constant velocity
relative to the fixed frame, agree on measurements of (circle all that apply)
a)
b)
c)
d)
an object's position
an object's velocity
an object's acceleration
an object's path
9. (6 pts.) Draw a clearly labeled free body diagram for a block of mass M being pushed by a constant
horizontal force F up an incline of angle  with respect to the horizontal. The velocity of the block is
constant. Use axes parallel and perpendicular to the incline. Assume friction is present.
I’ll let you handle this one. Just remember that the external force is horizontal, which means that it will have
components both along and perpendicular to the incline. Friction always opposes the motion (actual or
impending).
10. (6 pts.) Write out the equations of motion (Newton's 2nd law or sum of forces) in sufficient detail so
that you could solve for F in problem 9 given M, , and k. Do not solve for F, just write out the equations.
Clearly label sign conventions!
With up the slope positive, the sum of forces is F cos – k N – Mg sin = 0. With positive into the incline
surface, the sum of forces is F sin + Mg cos – N = 0.
11. (2 pts.) Suppose a tension T in a string of length L is required to maintain an object in a horizontal
circular path with uniform tangential speed v. If v is doubled, by what factor must L change to keep T
constant?
a)
1
4
b)
1
2
c) 2
d) 4
12. (6 pts.) A force F pulls a block up a rough incline at constant speed.
a) Identify all the forces acting on the block.
The force F, gravity, friction, and the normal force.
b) Tell whether the work done by each force is positive, negative, or zero.
F does positive work, the component of gravity along the slope does negative work, friction does negative
work, and the normal force does no work.
c) Write an algebraic expression relating the works.
W(by F) + W(by gravity) + W(friction) = 0 since K = 0 (constant speed).
13. (4 pts.) Label the following statements True or False.
_T___ The work done by a conservative force around a closed path is zero.
__T__ The work done by a conservative force is independent of the path taken.
__F__ The work done by a conservative force causes an increase in the potential energy associated
with that force. (assuming the work is positive)
__F__ If only conservative forces act, total kinetic energy is conserved.
14. (4 pts.) A system of particles moves under the influence of conservative external and internal forces.
Which of the following statement(s) is (are) true?
A)
B)
C)
D)
The total energy of an individual particle is conserved.
The total energy of the system is conserved.
The linear momentum of an individual particle is conserved.
The total linear momentum of the system is conserved.
a) A & B only
e) all are true
b) C & D only
f) none is true
c) A, B & C only
d) A, B & D only
15. (4 pts.) Consider a two-dimensional collision of unknown elasticity with no external forces. Label the
following statements True or False.
__T__ x- and y-components of total linear momentum are conserved separately.
__F__ Total kinetic energy is conserved.
__F__ The final particle velocities are dependent only on the geometry of the collision and not on
the particle masses.
__T__ The velocity of the center of mass of the two particles is constant.
16. (2 pts.) What are the rotational analogs of the linear variables x, v, and a?
a)  and 
b) , and 
c) , and  d) , and I
17. (2 pts.) The uniform object below has dimensions a<b<c. The axes shown are parallel to the
corresponding dimensions. If Ia, Ib, and Ic are the moments of inertia along axes parallel to those shown but
through the center of mass, arrange them in order from smallest to largest.
a
c
b
a
b
c
Ic < Ib < Ia
18. (4 pts.) Consider a constant torque  acting on a rigid body with moment of inertia I about some fixed
axis. If the body rotates through an angle  from rest, what is the resultant angular velocity of the object,
expressed in terms of the given variables?
Since W = K = ½ I 2 and W = , solve for  and get SQRT(2/I)
19. (4 pts.) A student sits on a frictionless stool and holds the axis of a heavy spinning wheel, one hand on
either side of the wheel. The axis is horizontal and the top edge of the wheel rotates away from the student.
If the student rotates the axis of the wheel to a vertical position in which his left hand is on top, which way do
he and the stool rotate, viewed from above?
a) clockwise
b) counter-clockwise
c) no rotation occurs
20. (4 pts.) Describe qualitatively the forces required to keep an object in static equilibrium if a) only two
forces act and b) only three forces act.
Only two forces – equal and opposite along the same line of action
Three forces – vector sum is zero, but lines of all three forces must intersect at some point.
21. (4 pts.) For simple harmonic motion, label the following statements True or False.
__F__ Position and acceleration are 90˚ out of phase.
__F__ Acceleration is zero when velocity is zero.
__T__ Velocity is maximum when position is zero.
__F__ Total energy is proportional to maximum displacement.
22. (2 pts.) If a grandfather clock were running slow, how could you adjust the pendulum to correct it?
(Circle one.)
a)
b)
c)
d)
Increase the length
Decrease the length
Increase the mass
Decrease the mass
23. (2 pts.) An ice cube (with no air bubbles) in a glass of water completely melts. The water level in the
glass
a) increases
b) decreases
c) remains the same
24. (10 pts.) Label the following statements True or False.
__F__ A wave described by y = f(x - vt) travels to the left.
__F__ Two traveling waves in the same medium add in quadrature (i.e., ytotal =
y12  y22 ).
__F__ A wave transmitted from one medium to another is never inverted.
__F__ A reflected wave pulse is inverted if the incident wave pulse travels from a medium with
slow wave speed to a medium with fast wave speed.
__T__ The wavelength of a wave measures its spatial periodicity.
__F__ For a wave in a string, transverse velocity and transverse position are 180˚ out of phase.
__F__ Two waves of the same frequency, phase, and propagation direction create a standing
wave.
__T__ No energy is transmitted by a standing wave.
__F__ The first antinode in a standing wave created in a string fixed at both ends is a distance of

from one end.
2
__F__ All harmonics (n = unrestricted integer) can be created in an organ pipe closed at only one
end.
25. (2 pts.) Your friend walks toward a wall carrying a vibrating tuning fork. You are leaning against the
wall. Compared to the sound you hear, the echo he hears is
a) higher in frequency
b) lower in frequency
c) the same frequency