A motor cycle starts from rest and accelerates along a straight path at `2m//s^(2)`. At the starting point of the motor cycle there is a stationary electric siren. How far has the motor cycle gone when the driver hears the frequency of the siren at `94%` of its value when the motor cycle was at rest ? (Speed of sound = `330ms^(-2))`

Options

A. `49m`
B. `98m`
C. `147m`
D. `196m`

Answer

B

Explanation

For motor cycle , `u=0`, `a=2ms^(-1)`
Observer is in motion and source is at rest, then apparent frequency, `n.=n(V-V_(0))/(V+V_(s))` and `S=(V^(2)-u^(2))/(2a)`