Q. Mass of moon is $7.34 \times 10^{22}$ kg. If the acceleration due to gravity on the moon is 1.4 $ms^{- 2}$, the radius of the moon is $(G = 6.667 \times 10^{11}Nm^{2}kg^{- 2})$
A) $0.56 \times 10^{4}$m
B) $1.87 \times 10^{6}$m
C) $1.92 \times 10^{6}$m
D) $1.01 \times 10^{8}$m
Explanation
(b) $g = \frac{GM}{R^{2}}\ or\ \ \ R = \sqrt{\frac{GM}{g}}$
$= \sqrt{6.67 \times 10^{- 11} \times 7.34 \times 10^{22}/1.4} = 1.87 \times 10^{6}\ m$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.