Given:
Velocity of car = 54 kmh−1 =
Frequency of the car f = 400 Hz
Velocity of sound in air = 335 ms−1
Wavelength in front of the car = ?
(a) Net velocity in front of the car = = 33515 = 320 m/s
(b) The frequency heard near the cliff is given by:
As we know,
.
(c) Here, = 15 ms.
Frequency of the reflected sound wave heard by the person sitting in the car:
(d) He will not hear any beat in 10 seconds because the difference of frequencies is greater than 10 (persistence of sound for the human ear is 1/10 of a second).