Q38 of 146 Page 145

A boy weighing 50 kg climbs up a vertical height of 100 m. Calculate the amount of work done by him. How much potential energy does he gain? (g = 9.8 m/s)

Given,

mass of the body, m = 50kg,


Acceleration due to gravity, g = 9.8 m/s2, height, h = 100m


Potential energy = Work done = mgh


= 50 × 9.8 × 100


= 59000J


= 59KJ


(At any point above the surface of the ground, the work done in raising the body is numerically equal to the potential energy)


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A body of mass 100 kg is lifted up by 10 m, Find:

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To what height should a box of mass 150 kg be lifted, so that its potential energy may become 7350 joules? (g = 9.8 m/s2)