Q. Gravitational potential difference between surface of a planet and a point situated at a height of 20 m above its surface is 2 joule/kg. if gravitational field is uniform, then the work done in taking a 5 kg body upto height 4 meter above surface will be :
(1) 2J (2) 20J (3) 40J (4) 10J
Here,
m = 5kg
V = 2 J/kg
h2 – h1 = 20 m
V = g(h2 – h1) = 2
g (20) = 2
=> g = 0.1 ms-2
Now work done in rising a mass of 5 kg by 4 m will be
W = Mgh
=> W = 0.1×5×4
=> W = 2J
Work done will be 2 Joule