A boy riding on a bicycle going at 12 km h^-1 towards a vertical wall whistles at his dog on the ground. If the frequency of the whistle is 1600 Hz and the speed of sound in air is 330 m s^-1, find (a) the frequency of the whistle as received by the wall (b) the frequency of the reflected whistle as received by the boy.

A sound source, fixed at the origin, is continuously emitting sound at a frequency of 660 Hz. The sound travels in air at a speed of 330 m s^-1. A listener is moving along the line x=336 m at a constant speed of 26 m s^-1. Find the frequency of the sound as observed by the listener when he is (a) at y = — 140 m, (b) at y = 0 and (c) at y = 140 m.

A train running at 108 km h^-1 towards east whittles at a dominant frequency of 500 Hz. Speed of sound in air is 340 m/s, What frequency will a passenger sitting near the open window hear 7 (b) What frequency will a person standing near the track hear whom the train has just passed? (c) A wind start blowing towards east at a speed of 36 km h^-1. Calculate the frequencies heard by the passenger in the train and by the person standing near the track.

A person standing on a road sends a sound signal to the driver of a car going away from him at a speed of 72 km h^-1. The signal travelling at 330 m s^-1, in air and having a frequency of 1600 Hz gets reflected from the body of the cur and returns. Find the frequency of the reflected signal as heard by the person.

A car moves with a speed of 54 km h” towards a cliff. The horn of the car emits sound of frequency 400 Hz at a speed of 335 m s^-1. (a) Find the wavelength of the sound emitted by the horn in front of the car. (b) Find the wavelength of the wave reflected from the cliff. (c) What frequency does a person sitting in the car hear for the reflected sound wave? (d) How many beats does he hear in 10 seconds between the sound coming directly from the horn and that coming after the reflection?