If an object of mass 2 kg is thrown up from the ground reaches a height of 5 m and falls back to the Earth (neglect the air resistance). Calculate
The work done by gravity when the object comes back to Earth

Explanation

When the object goes up, the displacement points in the upward direction whereas the gravitational force acting on the object points in downward direction. Therefore, the angle between gravitational force and displacement of the object is `180^(@)`.
When the object falls back, both the gravitational force and displacement of the object are in the same direction. This implies that the angle between gravitational force and displacement of the object is `0^(@)`.
`W_(down)=FDeltacos0^(@)`
`W_(down)=2 times 10 times 5 times (1)=100"joule"`
`" "cos0^(@)=1]`