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

Answer

D

Explanation

`n'=(v-v_(0))/(v)n=(94)/(100)n `
From (iii) `en^(n)` of motion `v^(2)=u^(2)+2as`
`rArr v_(0)^(2)=0+2as rArr v_(0)=sqrt(2as)`
`rArr (94)/(100)n=((v-sqrt(2as))/(v))nrArr s=98m`