1. what’s the velocity of a sound wave traveling through air at a temperature of 20°c (68°f)?
2. what’s the velocity of a sound wave traveling through air at a temperature of 18°c (64.4°f)?
3. identify the scenarios below as to whether they would increase, decrease, or not change the velocity of the sound wave. assume that no other changes are happening.
a. lowering the humidity of the air
b. increasing the temperature of the air
c. leaving the density of the air constant
d. changing the direction of the wind so that it’s blowing in the opposite direction of the sound wave
4.explain what must be true of component waves for reinforcement or interference to occur.
your response
1. v = 331 m/s + (0.6 m/s/c) × t
v = 331 m/s + (0.6 m/s/c) × 20°c
v = 331 + 0.6 × 20
v = 331 + 12
v = 343 m/s

2. v = 331 m/s + (0.6 m/s/c) × t
v = 331 m/s + (0.6 m/s/c) × 18°c
v = 331 + 0.6 × 18
v = 331 + 10.8
v = 341.8 m/s

3. a. decrease
b. increase
c. not change
d. decrease

4. if component waves have the same amplitude and same frequency, are in phase, and travel in the same direction, reinforcement occurs. the resultant wave travels in the same direction as each component wave and is in phase with the component waves. it has the same frequency and same wavelength, but the amplitude is twice as great as the amplitude of either component wave. if the two waves are out of phase and are moving molecules through the same distance in opposite directions, the resultant motion is zero. here interference occurs.

reinforcement and interference can occur within a resultant wave that results from waves with different frequencies.