Question

Shyam drops a ball of 100g from a building of North 10m.what will be Its kinetic energy at the height of 4m? what will happen to its total mechanicalenergy.givereason

Answer 1

Total height of the building= 10m

mass of the ball = 100g= 0.1 kg

The ball is dropped from the building and at a height of 4m, that is the ball travels (10-4)m= 6m from the top of the building after dropping.

At this point of height, velocity of the ball

v²=u²+2gs

v²=0+2×10×6     [u=0, as it starts from rest]

v²= 120

We know, Kinetic energy K.E = (1/2) mv²

                                           =(1/2)×0.1×120= 6J

Total mechanical energy of a body is the summation of its potential energy and kinetic energy which remains constant.

In this case, as the height decreasing its potential energy is transforming to kinetic energy. But the total mechanical energy is conserved.