AAPT Quiz
PhysicsBowl 2014 (Part 2)
26. A solid cube of iron and a solid cube of aluminum have equal mass. The cubes are placed into the same large pool of water so that each is completely submerged and resting on the pool’s bottom. Which object experiences the greater buoyant force from the water?
(A) The iron cube
(B) The aluminum cube
(C) The buoyant forces are equal.
(D) The mass of the cubes is needed to answer the question.
(E) The answer depends on whether the pool is filled with fresh water or salt water.
27. Two spherical, non-rotating planets, X and Y, have the same uniform density ρ. Planet X has twice the radius of Planet Y. Let g
_{X}
and g
_{Y}
represent the accelerations due to gravity at the surfaces of Planet X and Planet Y, respectively. What is the ratio of g
_{X}
: g
_{Y}
?
(A) 2:1
(B) 1:2
(C) 1:1
(D) 4:1
(E) 1:4
28. A waterproof speaker placed at the bottom of a swimming pool emits a sound wave that travels toward the surface of the water. In the water, the sound wave has a frequency f
_{water}
, wavelength λ
_{water}
, and wave speed v
_{water}
. When the sound wave enters the air it has a frequency f
_{air}
, wavelength λ
_{air}
, and wave speed v
_{air}
. Which one of the following relationships correctly compares the frequencies, wavelengths, and wave speeds of the waves in the air and water?
(A) f
_{water}
= f
_{air}
; λ
_{water}
= λ
_{air}
; v
_{water}
= v
_{air}
(B) f
_{water}
= f
_{air}
;
λ
_{water}
>
λ
_{air}
; v
_{water}
> v
_{air}
(C) f
_{water}
< f
_{air}
;
λ
_{water}
>
λ
_{air}
; v
_{water}
= v
_{air}
(D) f
_{water}
< f
_{air}
;
λ
_{water}
=
λ
_{air}
; v
_{water}
< v
_{air}
(E) f
_{water}
= f
_{air}
;
λ
_{water}
<
λ
_{air}
; v
_{water}
> v
_{air}
29. An electron with charge
-e
and mass
m
travels at a speed
v
in a plane perpendicular to a magnetic field of magnitude
B
. The electron follows a circular path of radius
R
. In a time
t
, the electron travels halfway around the circle. What is the amount of work done by the magnetic force on the electron in this time?
(A) zero
(B) -
π
evBR
(C)
π
evBR
(D) -2evBR
(E) -
π
mv/eB
30. Considering only the Moon-Earth system (ignore any influence of the Sun), which one of the following best expresses the magnitude of the Moon’s acceleration about the Earth?
(A) 3×10
^{−1}
m/s
^{2}
(B) 3×10
^{−2}
m/s
^{2}
(C) 3×10
^{−3}
m/s
^{2}
(D) 3×10
^{−4}
m/s
^{2}
(E) 3×10
^{−5}
m/s
^{2}
31. A toy crane exerts an upward force and delivers a useful power output of 0.10 W to raise a block vertically at a constant speed. At what constant speed will this crane raise a 0.20 kg block?
(A) 0.01 m/s
(B) 0.02 m/s
(C) 0.05 m/s
(D) 0.20 m/s
(E) 0.50 m/s
32. Planck’s constant is multiplied by the speed of light. The resulting value then is divided by three meters. This final value has the units of which one of the following quantities?
(A) Force
(B) Linear Momentum
(C) Speed
(D) Frequency
(E) Energy
33. An object moves with constant acceleration starting with velocity v
_{o}
= 5.00 m/s and ending with a velocity of
v
= -1.00 m/s in a time of 3.00 s. For this motion, what is the average speed associated with the object?
(A) 2.00 m/s
(B) 2.17 m/s
(C) 2.50 m/s
(D) 2.83 m/s
(E) 3.00 m/s
34. Two circular loops of resistive wire are placed next to each other as in the figure. The circular loop on the left is connected to a constant voltage source
V
. The resistance of this loop is increasing linearly with time. As the resistance is changing, what is the direction of the magnetic field at point P (the center of the left-hand loop) and what is the orientation of the conventional current in the right-hand loop (as viewed in the figure from above)?
(A) A
(B) B
(C) C
(D) D
(E) E
35. There are several statements presented below that attempt to describe physical phenomena. Which one of the following statements is correct?
(A) The coefficient of friction is a value always less than or equal to one, but greater than or equal to zero.
(B) For horizontal surfaces, the normal force acting on an object always cancels the gravitational force.
(C) An ideal gas’s temperature must change if both work is done and energy is exchanged as heat with it.
(D) Increasing the spacing between slits in the Young’s double slit experiment results in an increase in the spacing between the dark regions on a distant viewing screen.
(E) In electrostatic equilibrium, an electric field is perpendicular to the surface of a charged conductor.
36. A concave mirror with focal length
f
is shown in the figure. A real object now is placed to the left of the mirror. In theory, which one of the following choices best describes everywhere that it is impossible for an image to form from the mirror?
(A) Region II only.
(B) Regions II and III only.
(C) Regions III and IV only
(D) Regions II and IV only
(E) Regions I, II, and IV only
37. A new element is discovered and named PhysicsBowlium (atomic symbol
Phys
). Its entry onto the standard periodic table of elements appears as in the figure (with Helium shown as well). Given a sample of
Phys
which acts as a perfect monatomic ideal gas, what is the root-mean-square speed of the atoms of the gas if the sample is at 20°𝐶?
(A) 1.04 m/s
(B) 4.00 m/s
(C) 33.0 m/s
(D) 126 m/s
(E) 191 m/s
38. In the circuit shown, the switch S has been left open for a very long time. All circuits elements are considered to be ideal. Which one of the following statements best describes the behavior of the current through the switch S once it is closed?
(A) The current initially is 12 mA and decreases to a steady 3 mA.
(B) The current initially is 3 mA and increases to a steady 12 mA.
(C) The current initially is 9 mA and decreases to a steady 3 mA.
(D) The current initially is 6 mA and decreases to a steady 3 mA.
(E) The current is a steady 3 mA.
39. Two uniform disks, X and Y, have masses m
_{X}
< m
_{Y}
, equal radii, and equal initial non-zero kinetic energies. Each disk rotates counterclockwise in the plane of the page about a fixed frictionless axis through its center. As shown in the figure, a force
F
is applied tangent to each disk at its right edge for the same amount of time. After the forces are applied, let
L
represent the magnitude of the angular momentum about the center of a disk and
K
represent the kinetic energy of a disk. Which one of the following choices correctly compares these quantities for disk X and disk Y?
(A) L
_{x}
> L
_{Y}
; K
_{X }
< K
_{Y}
(B) L
_{X}
> L
_{Y}
; K
_{X}
> K
_{Y}
(C) L
_{X}
= L
_{Y}
; L
_{X}
= K
_{Y}
(D) L
_{X}
< L
_{Y}
; K
_{X}
< K
_{Y}
(E) L
_{X}
< L
_{Y}
; K
_{X }
> K
_{Y}
40. A small 1.35 kg mass is launched from the top of a cliff at an angle of 15.9° above the horizontal. When the mass reaches the ground 4.33 seconds later, its velocity is directed at 34.4° below the horizontal. What is the speed of the mass when it reaches the ground? Ignore air resistance.
(A) 60.7 m/s
(B) 54.1 m/s
(C) 46.4 m/s
(D) 43.3 m/s
(E) 38.8 m/s
All Division 01 students STOP HERE. Your last answer should be for #40. Numbers #41-#50 should remain blank for Division 01 students.
> All Division 02 students continue to Questions #41 – #50.
41. “No two electrons in an atom can have an identical set of the four quantum numbers.” is a statement most closely associated with which one of the following scientists?
(A) Albert Einstein
(B) Enrico Fermi
(C) Sheldon Cooper
(D) Wolfgang Pauli
(E) Isaac Newton
42. Plane-polarized light with intensity
I
is incident on a single polarizing sheet. If the intensity of the light become
(1/4)I
after passing through the polarizer, what is the angle between the transmission axis of the polarizer and the polarization plane of the incident light?
(A) 75°
(B) 67.5°
(C) 60°
(D) 30°
(E) 22.5°
43. A long rod of length
L
is pivoted about its left end. It is released from an angle
θ
above the horizontal. What is the magnitude of the angular acceleration of the rod about the pivot when the rod is released?
(A) (6g/L)cos
θ
(B) (6g/L)sin
θ
(C) (3g/2L)sin
θ
(D) (3g/2L)cos
θ
(E) (3g/L)sin
θ
44. A ray of monochromatic light enters the right-triangular glass as shown. The glass has an index of refraction of 2.00 and it is surrounded by air. Which one of the lettered rays shows the path of the light after it exits the glass?
(A) A
(B) B
(C) C
(D) D
(E) E
45. A long thin rod of mass
M
and length
L
is pivoted at one end so that it swings as a pendulum. The rod is set into simple harmonic oscillation and has a period of motion
T
. A second thin rod with mass
2M
and length
2L
also is pivoted at one end to swing as a pendulum. When this second rod is set into simple harmonic oscillation, what is its period?
46. A monatomic, ideal gas undergoes an isobaric process. During the process, the gas performs 80 joules of work on the surroundings. Which one of the following statements best describes the heat exchange during this process?
(A) 200 joules of energy was added to the gas.
(B) 200 joules of energy was removed from the gas.
(C) 80 joules of energy was added to the gas.
(D) 80 joules of energy was removed from the gas.
(E) It cannot be determined without knowing the change in temperature for the gas.
47. An air-filled parallel-plate capacitor of capacitance
C
is fully charged after being connected to a battery of voltage
V
. The battery then is disconnected and an insulating dielectric slab of constant
κ
is inserted between the capacitor’s plates, fully filling the region. What is the voltage between the plates once equilibrium is established with the dielectric in place?
(A)
κ
^{2}
V
(B)
κ
V
(C) V
(D) V/
κ
(E) V/
κ
^{2}
48. A laser beam with wavelength 632.8 nm shines onto a newly fabricated single slit. As a result, the width of the principal bright region on a viewing screen 1.25 m away is 1.00 m. Which one of the following best represents the size of the single slit opening?
(A) 0.79 µm
(B) 0.85 µm
(C) 1.01 µm
(D) 1.58 µm
(E) 1.70 µm
49. solid, uniform disk of mass
M
and radius
R
rotates clockwise about its center with an angular speed
ω
_{o}
. The disk then is placed onto a horizontal surface and begins moving only to the right, slipping as it rolls. The coefficient of friction between the floor and the disk is
µ
and the frictional force is considered constant throughout the motion. What is the angular speed of the disk when the disk starts rolling without slipping?
50. Two clocks, A and B, are synchronized on Earth. Clock A is placed onto a space ship that leaves Earth in a straight line with a speed of 2.40 × 10
^{8}
m/s. On Earth, a scientist with clock B has her telescope fixed directly on clock A. If each clock started at t = 0 s, what time does the scientist observe on clock A when clock B reads t = 90 s? Assume the time of acceleration for the ship leaving the Earth was negligible.
(A) 24 s
(B) 30 s
(C) 50 s
(D) 54 s
(E) 72 s
All Division 02 students STOP HERE. Your last answer should be for #50.
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at
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