Two sources of sound are moving in opposite directions with velocities `V_(1)` and `V_(2)(V_(1) gt V_(2))`. Both are moving away from a stationary observer. The frequency of both the source is 1700Hz. What is the value of `(V_(1)-V_(2))` so that the beat frequency observed by the observer is 10Hz. `V_("sound")=340m//s` and assume that `V_(1)` and `V_(2)` both are very much less than `V_("sound")`.

Options

A. `1m//s`
B. `2m//s`
C. `3m//s`
D. `4m//s`

Answer

B

Explanation

`1700{(340)/(340+V_(2))-(340)/(340+V_(1))}=10`
`rArr (1700xx340)/(340){(1-(V_(2))/(340))-(1-(V_(1))/(340))}=10`
or `(1700(V_(1)-V_(2)))/(340)=10" or " V_(1)-V_(2)=2m//s`