An object of mass 40 kg is raised to height of 5 m above the ground. What is its potential energy? If the object is allowed to fall, find its kinetic energy when it is half-way down.

Explanation

`V^(2)-u^(2)=2gh`
`V^(2)=2xx(10)xx(2.5)`
`V^(2)=50 m//s^(2)`
`K.E.=(1)/(2)mv^(2)`
`=(1)/(2)xx40xx50`
`=1000J`
`" " `OR
After P.E. half - way down
`E= m xx g xx h`
`=400xx10xx2.5`
` =1000J`