A particle of mass m lies at a distance r from the centre of earth. The force of attraction the particle and earth is F(r).
Answer & explanation
Correct answer: option 4
F = $\left\{\begin{array}{l}\frac{GMm}{r^2} r \geq r \\ \frac{4 \pi G \rho rm}{3} r<r\end{array}\right.$
where ρ is density of earth.