Question

A small source of sound vibrating at frequency 500 Hz is rotated in a circle of radius `100/2pi` cm at a constant angular speed of 5-0 revolutions per second. A listener situates himself in the plane of the circle. Find the minimum and the maximum frequency of the sound observed. Speed of sound in air `= 332 m s^-1`.

Answer 1

Correct Answer - A::D
Acording to given data
`Radius of the circle `=100/picm`
`=100/pixx10^-2m`
`=(1/pi)metres`
`omega=5rev/sec`
So the linear speed
`v=omegar=5/pi=(1.59)`
so, velocity of the source
`V_s=1.59m/s`
so the at the position A the observer will listen maximum and at the position B it will listen minimum frequency.
So apparent frequency at A
`=(332/(332+159))xx500~~515Hz`
So apparent frequency at B
`=(332/((332+159))xx500~~485GHz`