STUDENT NAME________________ STUDENT NUMBER:____________
CLOSED BOOK EXAM
DURATION: 100minutes
PART
I In the scantron sheet mark your answers to following 7 MC questions.
Answer all questions. This part is worth 48 points in total.
1.
The amplitude of a system moving with simple harmonic motion is
doubled. The total energy will then be:
A)
4 times larger
B)
3 times larger
B)
2 times larger
D)
the same as it was
E)
half as much
2.
A torsional pendulum consists of a solid disk (mass = 2.0 kg, radius = 1.0 m, Icm= mr
2
)
suspended by a
wire attached to a rigid support. The body oscillates about the support wire. If the
torsion
constant
is 16 N m. What is the angular frequency (in rad/s)?
A) 2
B) 4
C) 6
D) 8
E) one of the above
3.
A point source emits sound waves with a power output of 100 watts. What is the sound level
(in dB) at a distance of 10 m?
4.
The lowest A on a piano has a frequency of 27.5 Hz. If the tension in the 2.00 m string is 308 N, and onehalf wavelength
occupies the string, what is the mass of the wire?
5
A stretched string is observed to vibrate in three equal segments when driven by a 480 Hz oscillator. What is the
fundamental frequency of vibration for this string?
6.
A concave mirror has a focal length of 20 cm. What is the position of the object if the image
is upright and is two
times larger than the object?
A) 30
B) 205
C) 10
D) 40
E) 60
7.
Light strikes a diamond (
n
=
2 42
.
) immersed in glycerin (
n
=
1 473
.
) at an angle of 60°. What is
the angle of refraction
in the diamond?
University of Ottawa
PHY1322
Winter 2010
Test 2
March 26
Dr. A. Czajkowski
№ 1
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PART II
Solve 5 out of following 6 problems. On the front page clearly indicate which problems are you
submitting for marking. /Each problem is worth 10 points/
1
The fundamental frequency of an open organ pipe corresponds to middle C (261.6 Hz on the
chromatic musical scale).
The third harmonic (third resonance) of a closed organ pipe has the same frequency.
What is the length of each of the two pipes? (Take speed of sound to be 340m/s)
2
A train whistle (
f
= 400 Hz) sounds higher or lower in frequency depending on whether it approaches the stationary
observer or recedes from it.
(a) Prove that the difference in frequency between the approaching and receding train whistle is
f
v
u
v
u
f
2
2
/
1
/
2
−
=
Δ
where
u
is the speed of the train and
v
is the speed of sound. (8p)
(b) Calculate this difference for a train moving at a speed of 130 km/h. Take the speed of sound
in air to be 340 m/s. (2p)
3
A vertical plank of mass
m=3kg
and length
L=1m
is pivoted at one end.
The plank’s
other
end is supported by a massless spring of force constant
k=5N/m
. The moment
of inertia of the
plank about the pivot is
1
3
mL
2
. The plank is displaced by a small
angle
θ
from its
horizontal equilibrium position and released.
/The spring is not stretched when the plank is in
equilibrium position./
(a) Create a simplified diagram showing all the forces acting on the plank (3p)
(b) write down relevant Newton's Equations for the plank and
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 Fall '08
 CZAJKOWSKI
 Physics, Total internal reflection, Geometrical optics

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