Physics
101.002 Final Answers Dec. 13, 2007
Read each question and its set of answers very
carefully. There is only one best
answer for each question. Don’t be
afraid to ask questions of me during the exam.
Just raise your hand if you have one.
Useful information:
g = 32 ft/s2 = 9.8 m/s2.
1. The
period of pendulum A is 2 s. The period
of pendulum B is 1 s. Which pendulum is
longer in length?
(a) A
(b) B
(c) period
is different only because A has the larger mass
2. Both
transverse waves and longitudinal waves are capable of producing interference
patterns.
(a) True
(b) False
3. Sound
waves of very low frequency (humans can’t hear) are called
(a) sonic
(b) ultrasonic
(c) infrasonic
(d) supersonic
4. When
successive impulses are applied to a vibrating object in time with the natural
frequency of the object
(a) reverberation occurs
(b) refraction occurs
(c) resonance
occurs
(d) none
of the above
5. The
second harmonic on a guitar string has twice the speed of the fundamental for
that string.
(a) True
(b) False
6. You
are standing on the earth viewing a partial eclipse of the sun. In which shadow of the moon are you standing?
(a) the
penumbra
(b) the
umbra
(c) the
conundrum
(d) the
full
7. A beam
of blue light and a beam of red light have exactly the same energy. Which beam has the smaller number of photons?
(a) red
(b) blue
(c) they
both have the same number of photons
8. Green
light emitted by excited mercury vapor corresponds to a particular energy
transition in the mercury atom. A more
energetic transition might emit
(a) red
light
(b) blue
light
(c) either
red or blue light
(d) white
light
9. The
color of an opaque object is the same as the color of the light that is
(a) transmitted
(b) absorbed
(c) reflected
(d) all
of these
(e) none
of these
10. A blue
light beam and a yellow light beam are aimed at the same spot on a white
screen. What color does the spot appear
to be?
(a) green
(b) black
(c) blue
(d) yellow
(e) white
11. The
image in a plane mirror is real because you can see it with the naked eye.
(a) True
(b) False
12. Mirages
are produced by reflections of light off hot layers of air near the
earth's surface.
(a) True
(b) False
13. Every
body continues in its state of rest, or of uniform motion in a straight line, unless
it is compelled to change that state by forces impressed upon it. This is a statement of
(a)
(b)
(c) Galileo's
"Principia" law
(d) Aristole's
law of "De Revolutionibus"
(e) Copernicus'
geocentric universe
14. How
much speed does an object pick up in 2 seconds when it is undergoing a
constant acceleration of 2 m/s2 in a straight line?
(a) 2 m/s2
(b) 4 m/s2
(c) 2 m/s
(d) 4 m/s
15. You
throw a stone downward. It leaves your
hand with a speed of 10 ft/s. What is
its speed two seconds after leaving your hand?
(Neglect air resistance.)
(a) 10 ft/s
(b) 32 ft/s
(c) 42 ft/s
(d) 64 ft/s
(e) 74 ft/s
16. How
many
(a) 1
(b) 32
(c) 16
(d) 9.8
(e) 19.6
17. If the mass of a sliding block is somehow
doubled at the same time that the net force on it is doubled, what happens to
the resulting acceleration? It is it was before.
(a) the
same as
(b) twice
what
(c) one
half what
(d) can’t
be determined without knowing what numbers are involved
18. Which
of the following is an example of
(a) the
sun has a gravitational attraction for the earth and the earth has a
gravitational attraction for the moon
(b) a
book setting on a table has the force of gravity "pulling" on it and
a contact force "pushing" on it
(c) a
woman standing on an elevator exerts a force on the elevator compartment and
the compartment exerts a force on the elevator cables
(d) a
man standing on a set of scales exerts a force on the scales and the scales
exert a force on the man
19. Air
bags are used in cars to offer you protection during collisions by impeding
your motion toward the steering wheel and windshield. Which of the following is true concerning
their use?
(a) they apply the large force required to stop
you
(b) they reduce the impulse necessary to stop you
(c) they increase the time for you to come to a
stop
(d) all of the above
(e) none of the above
20. You
are standing on a frictionless surface of ice. You throw a 2‑kg object horizontally
with a velocity of 20 m/s. Your
mass is 100 kg. What is your horizontal
speed in m/s?
(a) 20
(b) 40
(c) 100
(d) 0.20
(e) 0.40
21. If you
push on an immovable wall for an hour, is there any work done on the wall?
(a) Yes
(b) No
22. Which
is more powerful?
(a) an
engine that does 1000 ftilb of work in 1 second
(b) an
engine that does 1000 ftilb in 1.5 seconds
(c) one
is just as powerful as the other since they can do the same amount of work
23. Doubling
one's velocity only doubles one's danger.
(a) True
(b) False
24. An
object of mass 6 kg is traveling at a velocity of 30 m/s. How much work was required to obtain this
velocity starting from a position of rest?
(a) 180 Joules
(b) 36 Joules
(c) 2700 Joules
(d) 5
Joules
(e) 180 N
25. Which
energy is an energy of position?
(a) kinetic
(b) heat
(c) potential
(d) force
x time
(e) watts
26. Can a
body have momentum without having energy?
(a) Yes
(b) No
27. A car
moving initially at 50 kilometers/hour skids with locked brakes to a stop
in 10 meters. How far in meters will the
car skid to a stop with locked brakes if it is traveling at
200 kilometers/hour?
(a) 20
(b) 60
(c) 90
(d) 120
(e) 160
28. If I have
a 100% efficient machine which lifts weights, how much energy must be supplied
to it to lift a 2000 lb weight 3 ft?
(a) 6660
ftilb
(b) 2000
lb
(c) 6000
hp
(d) 6000
ftilb
29. How
does a long pole help a tightrope walker to balance himself?
(a) the
pole increases his torque
(b) the
pole can be rotated rapidly to achieve balance
(c) it
doesn't help
(d) the
pole increases his rotational inertia
(e) the
pole makes the man heavier
30. Two
kids are sitting on a seesaw as shown.
If the kid on the left weighs 75 lb, what must the kid on the right
weigh in order to balance the seesaw?
(a) 50 lb
(b) 75 lb
(c) 100 lb
(d) 150 lb
(e) 200 lb
31. The
center of mass of a pole vaulter can actually pass under the bar as the pole vaulter
passes over the bar.
(a) True
(b) False
32. A
person with his back to a wall cannot bend down to touch his toes with his
hands without bending his knees. Why?
(a) his
center of mass would move beyond his area of support and he would fall
(b) angular
momentum would not be conserved
(c) he
can't develop the appropriate torque
(d) he
is in neutral equilibrium
33. In
class a metronome was used to discuss rotational inertia. When the sliding mass of the metronome was
placed as far from the pivot as possible, the period of the pendulum because the rotational inertia of the
pendulum .
(a) decreased,
decreased
(b) decreased,
increased
(c) increased,
increased
(d) increased,
decreased
34. The
object below is traveling in a circle at constant speed. What is the direction of the acceleration of
the object?
(a) tangent
to the circle
(b) between
tangent to the circle and perpendicular to the circle
(c) toward the center of the circle
(d) away
from the center of the circle
(e) there
is no acceleration
35. You
and a friend are riding on a playground merry‑go‑round. When you try to roll a ball to your friend
you notice that it curves. You report
that a force caused this curving. What
is the name of that force?
(a) centripetal
(b) circular
(c) centrifugal
(d) normal
(e) coriolis
36. In
shooting a rubber band one needs to in order to shoot the rubber band farther.
(a) stretch
the band as tight as one can
(b) fire
it faster
(c) warm
the rubber band before shooting
(d) put
spin on the rubber band
(e) take
longer in the firing of the rubber band
37. What
is required to change the angular momentum of a system?
(a) a
force
(b) a
spin
(c) a
jerk
(d) a
torque
(e) an
impulse
38. When
an ice skater spins with arms outstretched and pulls them inward, the speed at
which she spins increases. Does her
angular momentum increase?
(a) Yes
(b) No
39. The
non-spinning person below is holding a spinning bicycle wheel with its spin
"up." The person is standing on
a platform that is free to rotate. What
happens when the person flips the bicycle wheel over?
(a) nothing
(b) he
starts to spin with spin "down"
(c) he
starts to spin with spin "up"
(d) the
wheel stops spinning
40. If somehow the moon were moved to a distance twice as far
away from the earth as it is now, the force that the earth has for the moon
would
(a) be twice what it is now
(b) be one half of what it is now
(c) be four times greater than it is now
(d) be one fourth as much as it is now