Agalloping pony speeds past you at 5 m/s. the frequency of the sound produced by the hooves on the dirt is 221 hz. assume the speed of sound to be 342 m/s. what is the observed frequency of the hooves after the pony has passed your position?
1. 218 hz
2. 226 hz
3. 216 hz
4. 224 hz

Given:
speed of passing pony 5 m/s
frequency of the sound produced: 221 Hz
speed of sound 342 m/s

Let us use the Doppler Shift Formula:
Where the source is moving away from the observer at rest

f' = (v / v+vs) f
Where, vs = Velocity of the Source,
           v = Velocity of sound or light in medium,
           f = Real frequency,
           f' = Apparent frequency.

f'= [342 m/s / (342 m/s+5m/s)] * 221 Hz
f' = 0.9856 * 221Hz
f' = 217.8176 Hz or 218 Hz

The observed frequency of the hooves after the pony has passed your position is 218 Hz.