A listener moves towards a stationary source of sound with a velocity one fifth of the velocity of sound.
What is the percentage increase in the apparent freqency ?

Explanation

Hence listner moves towards the source.
`V_(L)=-V/5 V_(s)=0`
`V_(L)` -Velocity of listener
`V_(s)`- Velocity of source
V-Velocity of sound
Apparent frequency `=n. n.= [(V-V_(0))/(V-V_(s))]n`
`=((V+V/5))/(V-V_(s)) xx n`
`=[(5V+V)//5)/(V)]n`
`=[((6V)/(5))/(V)]n`
`=6/5 n=1.2n`
The percentage increase in apparent frequency `=[(n.-n)/(n)] xx 100`
`=[(1.2n-n)/(n)]xx 100`
=20%