Question

a body of mass 5 kg Falls freely from a height of 20 m from ground .find the kinetic energy of the body when it is at the height of 5 metre from ground.​

Answer 1

Taking 10 m/s² as acceleration due to gravity

Potential e = mgh = 5*10*20  = 1000 J

From law of conservation of energy we can conclude that energy can neither be created nor be destroyed but can be transformed into different types.

So when it is at a height of 20 m its potential energy = 1000J and kinetic energy is 0 as its at rest

When the body starts falling its potential energy decreases and kinetic energy increases as height decreases and velocity increases

∵ the question states 1/4th the actual distance, 5 m out of 20 m

∴ at that time Potential e = mgh = 5*10*5  = 250 J

as energy cannot be lost

⇒rest of the energy has been transformed to kinetic energy

Kinetic e= 1000-250 = 750 J

SO THE KINETIC ENERGY AT 5 METRE FROM THE GROUND IS 750 J

HOPE THIS HELPS ^_^