A bus is moving with a velocity of 5 m s - 1 towards a huge wall. The driver sounds a horn of frequency 165 Hz . If the speed of sound in air is 335 m s - 1 , the number of beats heard per second by a passenger inside the bus will be

Step-by-step solution

Apparent frequency v ′ = v v - v L v - v s = 165 355 + 5 355 - 5 ∵ v L = - 5   m   s - 1 ,   v s = 5   m   s - 1 = 165 × 340 330 = 170   Hz   Therefore, the number of beats heard =   170   -   165   =   5