A sound source S, emitting a sound of frequency 400 Hz and a receiver R of mass m are at the same point. R is performing SHM with the help of a spring of force constant K. At a time t = 0, R is at the mean position and moving towards the right, as shown. At the same time, the source starts moving away from R with some acceleration a. The frequency registered by the receiver at a time t = 10 s is 250 Hz. What is the time (in seconds) at which the corresponding registered frequency of 250 Hz was emitted by the source? [Given that `(m)/(K)=(25)/(pi^(2))` and amplitude of oscillation = `(100)/(pi) m, V_("sound")` = 320 m s^(-1)]`

Answer

8