Physics of Music Physics 121

Griffioen 19 October 1994

Quiz 3

  1. A wave passes from a high-velocity to low-velocity medium across the diagonal shown below, and reflects from the sides of the box. Carefully sketch the path of the wave. How does the original direction compare to the final direction?
  2. Give four examples of how and why your aural world would be different if all the laws of physics were the same except that there was no diffraction of sound waves.
  3. What are the metric units for force, work, power, and intensity?
  4. What is the SIL for the following intensities: 10-6 W/m2 and 1/10 W/m2?
  5. At 10 feet from your power speakers you record a SIL of 100 dB while playing an old Grateful Dead album. Because you cannot hear the subtleties of the music, you get closer. At what distance will you reach the threshold of pain (120dB)?
Extra Credit: If an observer and a source of sound are moving toward each other, both with speed v, and the source emits a frequency f0, what frequency will the observer hear?
College of William and Mary, Dept. of Physics
matt@physics.wm.edu