We know that
Gravity of earth attracts all objects towards earth
Example -
A ball falls towards ground because of force of gravity of earth
But if we pick up the ball, we are actually working against gravity
Hence, we can say that
Work done in lifitng a body is work done against gravity
How to Calculate Work Done Against Gravity
We know that
Work = Force × Distance
Calculating Force
Here Force is Gravitational force
We know that
Force = Mass × Acceleration
Gravitational Force = Mass × Acceleration due to Gravity
F = m × g
Calculating Distance
We know that Distance in case of body falling to earth/from earth is Height of Object
So in this case
Distance = Height
s = h
Now we know that
Work = Force × Distance
W = F × s
W = m × g × h
Height does not depend on path of the object.
Work Done = m × g × h
Here, height is measured from initial and final points, it does not depend on path travelled by the object
