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 reaches 5 m height

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^(@)`.
The work done by gravitational force in the upward motion.
Given that `Deltar=5m and F = mg`
`" "W_(up)=FDeltar costheta=mgDeltar cos180^(@)`
`W_(up)=2 times 10 times 5 times (-1)=-100"joule"`.
`" "[cos180^(@)=-1]`