Write down an expression for the observer frequency when both source and observer are moving relative to each other in the same direction.

Explanation

Apparent frequency of sound heard by an observer.
`v'= [ (v-v_(0))/(v-v_(s))]v `
where v= frequency ofsound
v=velocity of sound
`v_(0)=` velocity of observer
`v_(S) = ` velocityof source