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(B) The apparent frequency $f'$ heard by an observer moving away from a stationary source is given by the Doppler effect formula: $f' = f \left( \frac

Vedclass · Accepted Answer

$98$

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(B) The apparent frequency $f'$ heard by an observer moving away from a stationary source is given by the Doppler effect formula: $f' = f \left( \frac{v - v_o}{v} ight)$,where $v$ is the speed of sound and $v_o$ is the velocity of the observer.Given $f' = 0.94f$,we have $0.94f = f \left( \frac{330 - v_o}{330} ight)$.$0.94 = \frac{330 - v_o}{330} \implies 310.2 = 330 - v_o \implies v_o = 330 - 310.2 = 19.8 \,m/s$.The motorcycle starts from rest $(u = 0)$ with acceleration $a = 2 \,m/s^2$. Using the equation of motion $v_o = u + at$:$19.8 = 0 + 2t \implies t = 9.9 \,s$.The distance travelled $s$ is given by $s = ut + \frac{1}{2}at^2$:$s = 0 + \frac{1}{2} 	imes 2 	imes (9.9)^2 = 98.01 \,m$.Thus,the distance is nearly $98 \,m$.

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