# Properties of sound waves

1. Sound waves travel through an aluminum bar at a speed of 1400 m/s. If the frequency of the sound wave is 880 Hz, what is the distance between crests on a sound wave traveling through aluminum?

2. An airplane flies horizontally at a constant speed, piloted by rescuers who are searching for a disabled boat. When the plane is directly above the boat, the boat's crew blows a loud horn. By the time plane's sound detector receives the horn's sound, the plane has traveled a distance equal to one-half its altitude above the ocean. (The speed of sound is 343 m/s.) If it takes the sound 4.00s to reach the plane, determine

a) the altitude of the plane, and

b) its speed, in m/s. What is its speed in knots (nautical miles per hour)?

3. Estimate the wavelength of a 1500 Hz sound wave in air. Assume standard temperature and pressure.

4. A clarinet acts as a closed-ended air column. If its bottom note has a frequency of 130 Hz, how long is the column?

5. The sound of a truck horn, observed when the truck is stationary, is 440 Hz. A drunk is sitting in the middle of the road at night. He sees the truck's headlights, and hears a 500 Hz horn. How rapidly is the truck approaching him, in m/s2? In mph? (As before, assume the speed of sound in air is 343 m/s.)

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