Question

A solid sphere is of density $J$ and radius $R .$ The gravitational field at a distance $R$ from the centre of the sphere, when $r < R$ is:

• A. $\frac{J \lambda G R^{3}}{r}$
• B. $\frac{4 \lambda G J r^{2}}{3}$
• C. $\frac{4 \lambda G J R^{2}}{3 r^{2}}$
• D. $\frac{4 \lambda G J r}{3}$

Answer 1

Answer: (D)

Intensity $I=\frac{G M r}{R^{3}}$
$=\frac{G r}{R^{3}}\left(\frac{4}{3} \pi R^{3} J\right)$
$=\frac{4 \lambda G r J}{3}$