Question

A particle of mass $m$ lies at a distance $r$ from the centre of earth. The force of attraction between the particle and earth as a function of distance is $F(r)$,

• A. $F(r) \propto \frac{1}{r^{2}}$ for $r< R$
• B. $F(r) \propto \frac{1}{r^{2}}$ for $r \geq R$
• C. $F(r) \propto r$ for $r< R$
• D. $F(r) \propto \frac{1}{r}$ for $r< R$

Answer 1

Answer: (B), (C)

Outside the earth surface, as $g$ varies inversely proportional to square of the distance from center of earth option (A) is correct and inside the earth as $g$ varies as directly proportional to the distance option (C) is correct.