Question

derive the expression for potential energy of a body above the ground level ?

Answer 1

w.d.= Fs
w.d. over ground level :-
(mg)h..... ( here f= ma[a=accn due to gravity ]. & s = dist. = height [above ground ])


hence w.d. = mgh

Answer 2

The potential energy of a body is due to its higher position above the earth and is equal to the work done on the body, against gravity, in moving the body to that position.

Suppose a body of mass 'm' is raised to a height 'h' above the ground. The force acting on the body is gravitational force of earth i.e. m *g acting in downward direction. To lift the body above the surface of the ground, we need to do work against the force of gravity. Then,

Work done = Force * Distance
So, W = m * g * h

This work gets stored up in the body as potential energy. Thus,

Potential energy = m * g * h
Or P.E. = m* g * h

where m = mass of the body
g = acceleration due to gravity
h = height of the body above the ground