Q. A body of mass m is taken from the earth's surface to the height equal to twice the radius (R) of the earth. The change in potential energy of body will be
A) 2mgR
B) (2/3)mgR
C) 3mgR
D) (1/3)mgR
Explanation
[Solution from source] ΔU = GMm/R − GMm/3R = (2/3)GMm/R = (2/3)mgR, using GM = gR². The answer 2mgR comes from wrongly using mgh with h = 2R, which is valid only for heights much smaller than R. Answer (2).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.