Two vehicles, each moving with speed `u` on the same horizontal straight road, are spproaching each other. Wind blows along the road with velocity `w`. One of these vehicles blows a whistle of frequency `f_(1)`. An observer in the other vehicle hears the frequency of the whistle to be `f_(2)`. the speed of sond in still air is `VC`. the correct statement `(s)`is (are)

Options

A. (a) If the wind blows from the observer to the source, `f_(2)gtf_(1)`
B. (b) If the wind blows from the source to the observer , `f_(2)gtf_(1)`
C. ( c ) If the wind blows from the observer to the source, `f_(2)ltf_(1)`
D. (d) If the wind blows from the source to the observer , `f_(2)ltf_(1)`

Answer

A, B

Explanation

(a,b) Source Observer
`S rarr_u u_larrO`
`f_(1)` `f_(2)`
Caes1: Wind blows from observer to source
`f_(2) = f_(1) [((V + w) + u)/((V - w) - u)]` :. `f_(2) gt f_(1)`
Caes1: Wind blows from observer to source
`f_(2) = f_(1) [((V + w) + u)/((V + w) - u)]` :. `f_(2) gt f_(1)`
(a) and (b) are correct options