A boy travelling in a car at a speed of 108Km/h came to rest after applying breaks. Before coming to rest it covers 30m. It's acceleration is

### Asked by 2103030034 | 28th Aug, 2021, 03:06: PM

Expert Answer:

### Initial speed 108 km/h = 108 × (5/18) = 30 m/s
acceleration is determined from equation of motion
" v^{2} = u^{2} + (2aS) "
where v = 0 is final speed because the vehicle comes to rest finally , u = 30 m/s is initial speed ,
a is acceleration and S is distance travelled before coming to rest and after applying break .
Hence we get , acceleration a = - u^{2} / (2S) = - ( 30 × 30 ) / ( 2 × 30 ) = -15 m/s^{2}

^{2}= u

^{2}+ (2aS) "

^{2}/ (2S) = - ( 30 × 30 ) / ( 2 × 30 ) = -15 m/s

^{2}

### Answered by Thiyagarajan K | 28th Aug, 2021, 09:46: PM

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