Question
Question: If g is acceleration due to gravity on the earth's surface the gain in the potential energy of an ob...
If g is acceleration due to gravity on the earth's surface the gain in the potential energy of an object of mass m raised from the surface of the earth to a height equal to the radius R of the earth is -
A
21 mgR
B
2 mgR
C
mgR
D
41 mgR
Answer
2 mgR
Explanation
Solution
At a distance x, from the centre of the earth, gravitational force :
F = x2GMm
dw = fdx = dx
w = dx = GMm
= gR1m [R1−R+h1]
\ Gain in potential energy
= gR2m 2mgR