Problems p 265
3. Find correct speed of sound for given
temperature; then d = vt
4. Again, find speed of sound at given temperature;
t = v/t
6. Use equation 5 on p. 263. Use corrected
speed of sound at given temperature for v; vs is speed of source, which is given in km/hr
and must be converted to m/s to match units
of speed of sound. (584 Hz or 580Hz with
2 sig figs)
9.(a) Use I = P/A ; For the area, use the surface area of
a sphere (p 689) with a radius equal to the
given distance from the speaker. (0.490 W/m2) (b)Then use this intensity related to the
threshold of hearing with the equation on
p 257. Be careful entering exponents into
your calculator or you'll get the wrong answer.
(117dB)
Problems p 278
2.(a) Use equation on p 274 for closed-end
tube to find wavelength using the given length
and diameter. (b) Use temperature/speed relationship
to work backwards and find temperature difference
from 0.
3. Beat frequency = difference between two
frequencies sounded together. The question
here is whether the fork with the clay will
vibrate at a higher frequency or a lower
frequency because of the clay stuck to it.
5. Use law of tensions equation; be caruful
with those square roots! (240N)
8. Listener hears (a) average frequency,
(b) pulsating at beat frequency (problem
3).
12.(a) Find wavelength using given diameter
and length using open-ended tube equation
on p 275. To find fumdamental frequency,
you will have to know the speed of sound
at the given temperature. Then use wave speed
equation to find frequency. (130 Hz) (b)
For harmonics, remember open-ended tubes
produce all harmonics.
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