Question

An object of mass 1 kg is taken to a height from the surface of earth which is equal to three times the radius of earth. The gain in potential energy of the object will be
[If, g = 10 ms-2 and radius of earth = 6400 km]

• A. 48 MJ
• B. 24 MJ
• C. 36 MJ
• D. 12 MJ

Answer 1

Answer: (A)

48 MJ

Answer 2

The gain in potential energy of the object,
ΔU=Uf–Ui
ΔU=−$\frac{GMm}{4R}+\frac{GMm}{R}$
$ΔU=\frac{3GMm}{4R}$
$ΔU=\frac{3}{4}mgR$
$ΔU= 48 x 10^6J$
$ΔU= 48 MJ$
So, the correct option is (A): 48 MJ