A truck running at 72 km/h is brought to rest over a distance of 25 m.Calculate the retardation and time for which brakes are applied ?

Asked by nishola82 | 22nd May, 2018, 11:44: PM

Expert Answer:

Initial speed = 72 km/h = 72×(5/18) = 20 m/s.
 
to get reatardtaion, equation to be used is " v2 = u2 - 2×a×S " ,
where v is final speed ( v=0 here ), u is initial speed, a is retardation and S is distance travelled
 
hence retardation a = (20×20) / (2×25) = 8 m/s2
 
time t is obtained using equation " v = u - a×t ", with v = 0 
 
hence time t = 20/8 = 2.5 s

Answered by Thiyagarajan K | 23rd May, 2018, 12:32: PM

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