Q. A body of weight 500 N on the surface of the earth. How much would it weigh half-way below the surface of the earth?
A) 125 N
B) 250 N
C) 500 N
D) 1000 N
Explanation
(b) Weight on surface of earth, $mg = 500N$ and weight below the surface of earth at
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ d = \frac{R}{2}$
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ mg^{'} = mg\left( 1 - \frac{d}{R} \right)$
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ = mg\left( 1 - \frac{1}{2} \right)$
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ = \frac{mg}{2} = 250N$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.