An observer moves towards a stationary source of sound with a velocity one-fifth of the velocity of sound. Calculate the percentage increase in the apparent frequency?

Explanation

Here observer moves towards the stationary source.
`:.v_(0)=-(v)/(5),v_(s)=0`
Apparent frequency,
`v'=(v-v_(0))/(v-v_(s))xxv=(v+(v)/(5))/(v-0)xxv=(6)/(5)v=1.2v`.
The percentage increase in apparent frequency,
`(v'-v)/(v)xx100=(1.2v-v)/(v)xx100`
`=(0.2v)/(v)xx100=20%`.