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 a cyclist is moving at a uniform speed of 20 m/s for 30 s.He then stops pedalling and stops in next 10 s.Calculate : (1) average retardation ? (2) total distance travelled ?
Asked by nisha_vini29 | 22 May, 2018, 11:16: PM
answered-by-expert Expert Answer
Uniform speed 20 m/s for 30 s. 
Distance S1 travelled is given by, S1 = speed×time = 20×30 = 600 m
 
retardation a is obtained from "v = u - a×t ", where v is final speed (v=0 here ), u is initial speed and t is time. 
 
retardation a = u / t = 20 / 10 = 2 m/s2  .
 
Distance S2 covered while retarding :-  S2 = u×t - (1/2)×a×t2  = 20×10 - (1/2)×2×10×10 = 100 m
 
Total distance S1+S2 = 600+100 = 700 m
Answered by Thiyagarajan K | 23 May, 2018, 02:49: PM

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