Q51 of 146 Page 145

A weightlifter is lifting weights of mass 200 kg up to a height of 2 metres. If g = 9.8 m/s2, calculate:

(a) Potential energy acquired by the weights.


(b) Work done by the weightlifter.

(a) Given,


Mass, m = 200kg


Acceleration due to gravity, g = 9.8m/s2


Height, h = 2m


(a) We know,


P.E = mgh


= 200 × 9.8 × 2


=3920 J.


(b) Work done = Potential energy gained = 3920 J.


(Since, 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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