A body of mass 25 kg is raised to the top of a building 10 m high and then dropped freely under gravity (g = 10 m/s2):
(a) Calculate the work done in raising the body to the top of the building.
(b) What is the value of the gravitational potential energy at the top of the building?
(c) By what factor will the gravitational potential energy of the same body increase if it is raised to the top of a multistorey building 30 m high?
(d) When will the kinetic energy of the body be maximum?
A bag of wheat weighs 200 kg. To what height should it be raised so that its potential energy may be 9800 joules? (g = 9.8 m/s2).
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 ? Take g = 9.8 m/s2.
Mass of the boy, m = 50 kg
Acceleration due to gravity, g = 9.8 m/s2
Vertical height that the boy climbed up, h = 100 m
Work done by the boy = mgh
= 50 x 9.8 x 100
= 49000 J
= 4.9 x 104 J
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