Question
A body of man 100 kg travelled 10 m before coming to rest. If μ = 0.4, work done against friction is (motion is happening on horizontal surface, take g = 10 m/s2)
Options :
4500 J
5000 J
4200 J
4000 J
Answer :
4000 J
Solution :
V2/ 2a = S (a = µg)
V2 = 2 × µgs
V2 = 2 x (.4) x 10 x 10
V2 = 80
Wf = Δk
= -1/2 × 100 × 80
Wf = -4000
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