Q. The distance between centre of the earth and moon is $384000\ km$. If the mass of the earth is $6 \times 10^{24}\ kg$ and $G = 6.66 \times 10^{- 11}Nm^{2}/kg^{2}$. The speed of the moon is nearly
A) $1\ km/sec$
B) $4\ km/sec$
C) $8\ km/sec$
D) $11.2\ km/sec$
Explanation
(a) $v = \sqrt{\frac{GM}{r}} = \sqrt{\frac{6.67 \times 10^{- 11} \times 6 \times 10^{24}}{384000 \times 10^{3}}} = 1\ km/s$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.