Q 11-07-026NEETJEE MainEasy
A satellite orbits the Earth at a height equal to the Earth's radius $R$. If $g$ is the acceleration due to gravity at the surface, its orbital speed is
Answer: (B) $\sqrt{\dfrac{gR}{2}}$
Concept. $v = \sqrt{\dfrac{GM}{r}}$ with $GM = gR^2$, $r = 2R$.
Step 1. Substitute. $v = \sqrt{\dfrac{gR^2}{2R}} = \sqrt{\dfrac{gR}{2}}$.
Answer. $\sqrt{\dfrac{gR}{2}}$ (Option B).
Solution by Sreeraj P, M.Sc Physics