Write the expression for apparent frequency for source of sound moving towards a stationary observer.

Explanation

`f = (f_(0)(v))/(v-v_(s))` where, `v =` velocity of sound in air
`v_(a) =` velocity of source,
`f_(0)=` true frequency
Also `f~~f_(0) (1+ ( v_(s))/ (v))` `f = ` apparent frequency