Gravitational potential difference between surface of a planet and a point situated at a height of 20 m above its surface is 2joule/kg. if gravitational field is uniform, then the work done in taking a 5kg body of height 4 meter above surface will be-:

Options

A. 2J
B. 20 J
C. 40 J
D. 10 J

Answer

A

Explanation

`DeltaV=-E_(g).dr`
Because field is uniform
`therefore2=-E_(g).20impliesE=-(1)/(10),DeltaV=+(1)/(10)[4]=(2)/(5)`
work done in taking a 5 kg body to height 4 m
=m (change in gravitational potential)
`=5[(2)/(5)]implies2J`