A whistle of frequency 500 Hz, tie to the end of a string of length 1.2m, resolves at 400 rev/min. A listener standing some distance away in the plane of rotation of whistle hears frequency in the range of (speed of sound=$340\ ms^{- 1}$)

Question

Dr. Abubacker · Accepted Answer

(d) Velocity $v_{s} = r\omega = r.2\pi v$
$= 1.2 	imes 2 	imes 3.14 	imes \left( \frac{400}{60} ight) = 50ms^{- 1}$
$v_{\min\ } = \frac{v}{v + v_{s}}v$
$= \frac{340}{340 + 50} 	imes 500 = 436\ Hz\ $
$v_{\max\ } = \frac{v}{v - v_{s}}v$
$= \frac{340}{340 - 50} 	imes 50$0
=586 Hz

Q. A whistle of frequency 500 Hz, tie to the end of a string of length 1.2m, resolves at 400 rev/min. A listener standing some distance away in the plane of rotation of whistle hears frequency in the range of (speed of sound=$340\ ms^{- 1}$)

Explanation

Reviewed by Dr. Abubacker

Want more practice?