A train is moving with constant speed along a circular track. If length of the train is one fourth of length of circular track then which of the following is/are correct options (Assume that sound source is at engine and speed of engine is very less than speed of sound ):

Explanation

`f_(obs)=(f[v_s+v cos theta])/([v_s+v cos theta])=f`
`lambda_(obs)=(v_s+v cos theta)/f`
For any observer in train frequency observed is equal to original frequency but observed wavelength is more.