An observer moves towards a stationary source of sound, with a velocity one-fifth of the velocityof sound, What is the percentage increase in the apparent frequency ?

v0=v5⇒v0=3205=64ms−1When observer moves towards the stationary source, thenn′=v+v0vn⇒n′=320+64320n or n′=384320n or n′n=384320The percentage increase in the apparent frequency n′n−1100%=384320−1100%=20%