Two tuning forks A and B are vibrating at the same frequency 256 Hz. A listener is standing midway between the forks. If both tuning forks move to the right with a velocity of `5(m)/(s)`, find the number of beats heard per second by the listerner (speed of sound in air is `330(m)/(s)`).

Explanation

Tuning fork A is approaching the listener. Therefore apparent frequency of sound heard by listener is
`n_S=(v)/(v-v_S)n_A=(330)/(330-5)xx256=260Hz`
Tuning fork B is recending away from the listener. There fore apparent frequency of sound of B heard by listener is
`n_S=(v)/(v+v_S)n_B=(330)/(330+5)xx256=252Hz`
Therefore the number of beats heard by listener per second is
`n_A'=n_B'=260-252=8`