A small source of sound has mass M and is attached to a spring of force constant K. It is oscillating with amplitude `A=V/20 sqrt(M/K)` where V is speed of sound in air. The source of sound produces a sound of frequency `f_(0)=399 Hz`.
(a) Find the frequency of sound registered by a stationary observer standing at a distant point O.

(b) Let `Delta t_(1)` be the time interval during which the registered frequency changes from 420 Hz to `(399xx40/39) Hz` and `Delta t_(2)` be the time interval during which the observed frequency changes from `399 Hz` to `(399xx40/41) Hz`. Which is large `Delta t_(1)` or `Delta t_(2)`?

Answer

(a) `380 hz le f le 420 Hz`
(b) `Deltat_(1) gt Delta t_(2)`