Physics (work)

Calculate the work done on a cyclist if a braking force of 40 N [backward] slows the cyclist from 20 m/s to 15 m/s in 2.0 s.

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  1. work done is force times distance
    distance is speed times time force is constant so acceleration is constant and speed is average of beginning and end
    v = (20 + 15)/2 = 10 + 7.5 = 17.5 m/s
    so
    distance = 17.5 m/s * 2 s = 35 meters
    so work done is -40*35 Joules

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