(a) A truck of mass 1870 kg travelling at 80 km/h braked to 55 km/h then continued at that speed. How much work was done by the brakes during that period?
I just wanted to check my answer... 243334 J ??
Vo = 80km/h = 80000m/3600s = 22.22 m/s.
V = 55km/h = 55000m/3600s = 15.28 m/s.
Work = KE1-KE2 = o.5m*Vo^2-0.5m*V^2 =
935*22.22^2 - 935*15.28^2 = 461,636 -
218,302 = 243,334 J.