學生討論區

waistyle二星初級會員 2011-2-13 16:18#1

An athlete lifts a 10kg dumbbell vertically by 40cm

assuming that the dumbbell is lifted at a constant velocity find the work done by the athlete on it

NaozumiVIP會員 2011-2-13 23:42#2

constant velocity 即係作用係 dumbbell的resultant force = 0
所以work = 10 x g x 0.4     (0.4 m = 40 cm)
               = 10 x 10 x 0.4
               = 40 J

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