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Physics 1B – Spring 2011: Practice Midterm 1
Problem 1:
Consider two speakers, both on the yaxis, separated by a distance d=2 meters, and with
the bottom speaker at the origin.
Each speaker emits the same sound wave, in phase,
with frequency
f
0
= 514 Hz.
a)
Determine which on the positive xaxis will exhibit constructive and destructive
interference
b)
The top speaker is now removed, and a moving reflecting surface is placed to the
right of the remaining speaker and is moved toward it with speed v
surface
=2 m/s.
What frequency would a listener standing at the location of the speaker hear
reflected back from the moving surface?
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View Full DocumentProblem 2:
This problem walks you through a derivation of standing waves produced by two
speakers.
You will need the angle addition formula for cosines:
cos(a+b) = cos(a)cos(b)  sin(a)sin(b)
a)
Consider two speakers on the xaxis a distance D apart from each other.
Each
emits a wave with the same wavelength, frequency, and phase (you can take the
phase to be 0) in all directions.
Let’s place the origin at the location of the left
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 Spring '11
 Corbin

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