A bat flies perpendicular to a wall at 6m/s emitting a sound of frequency 45000 Hz. How many no. of beats it hears per second if the velocity of sound in air is 340 m/s ?

On the off chance that the sound achieves the eyewitness in the wake of being reflected from a stationary surface and the medium is additionally stationary, the picture of the source in the reflecting surface will turn into the wellspring of the reflected sound. 

v = v [c – v0/c – vs] 

v0, versus are +ve on the off chance that they are guided from source to the onlooker and – ve on the off chance that they guided from eyewitness to source. 

v = 45000/[340– (- 6)/340– 6] = 334 Hz