Question

Calculate the work done the breaks the car mass is 1000kg. When the speed is reduce 20m per second to 10 m per second

Answer 1

Work done by the brakes of a car would be the net change taken place in the KE of the moving car, W = 1/2 x m [(v2)^2 -(v1)^2]
                                   W = 1/2 x 1000 [(10)^2 - (20)^2]
                                   W = 500(100 - 400)
                                   W = 500 x (-300) =  -150000 = -1.5 x 10^5 joule

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