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A motor cycle starts from rest and accelerates along a straight path at 2 m/s^(2). At the starting point of the motoer 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^(-1) ) |
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Answer» 146 m ` V. = ((V- v)/(V)) ` y ` (94)/(100) V = (V - v)/(V) ` V `rArr "" 94 V =100 V - 100 v` `rArr "" 100v = 6 `v 100v= 6V `v = (6 xx 330)/(100) = 19.8` m/s Now `v^(2) - u^(2) = ` 2AS `rArr (19.8)^(2) - 0 = 2 xx 2s` S= 96 m `rArr ` CHOICE (d). |
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