Q. Two identical solid copper spheres of radius $R$ are placed in contact with each other. The gravitational attraction between them is proportional to
A) $R^{2}$
B) $R^{- 2}$
C) $R^{4}$
D) $R^{- 4}$
Explanation
(c) $F = \frac{G \times m \times m}{(2R)^{2}} = \frac{G \times \left( \frac{4}{3}\pi R^{3}\ \rho \right)^{2}}{4R^{2}} = \frac{4}{3}\pi^{2}\rho^{2}R^{4}$
$\therefore F \propto R^{4}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.