Question

Two sources S1 and S2 of same frequency f emits sound . The source are moving as shown with speed u each .A stationary observer hears that sound . The beat frequency is

Answer 1

Explanation:

Observer mowing away from S1 :

Apparent frequency f1=fo[vv−vo]

So, f1= 324[344344−vo] ........(1)

Observer mowing towards S2 :

Apparent frequency f2=fo[vv+vo]

So, f2= 320[344344+vo] ........(2)

Since, the observer hears no beats, so f1=f2

Or 324[344344−vo]= 320[344344+vo]

Or 324[344−vo]=320[344+vo]

⟹ vo=2.1 m/s