A small source of sound vibrating at a frequency 500   H z is rotated along a circle of radius 100 π cm at a constant angular speed of 5 revolutions per second. The minimum and maximum frequency of the sound observed by a listener situated in the plane of the circle is (Speed of sound is 332   ms - 1 )

Step-by-step solution

In one case the source is moving away and in one case this is moving towards while the observer is in rest so using Doppler shift in sound, f = f 0 v v ± v s , here the angular velocity is given, ω = 5   rev   s - 1 and the radius of the circle is, 1 π   m so the velocity of the source is, v s = ω r = 5 × 1 π = 1 . 59   m   s - 1 so apparent frequency, f = f 0 v v ± v s = 500 332 332 ± 1 . 59 = 485 . 4   Hz   &   515 . 5   Hz