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A speeder in an automobile passes a stat...

A speeder in an automobile passes a stationary policeman who is hiding behind a bil board with a motorcycle. After a `2.0` sec delay (reaction timwe) the policeman accelerates to his maximum speed of `150km//hr` in `12 sec` and catches the speeder `1.5km` beyond the billboard. find the speed of speeder in `km//hr`.

Text Solution

Verified by Experts

The correct Answer is:
`122.7 km//hr`
distance convered in accelerated motion
`= (1)/(2) xx ((12)/(3600)h) xx 150 Km// h`
`(1)/(4)km = 0.25 Km`
Remaining distance `(.5 -0.5) = 1.25 km` is convered with speed `150km//h.`so time taken
`= (1.25km)/(150km//h) = (1)/(120) h = 30sec`
speed of speeder `= (1.5 xx 3600)/(44)km//h`
`= 122.7 km//h`
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