Two spherical planets $P$ and $Q$ have the same unfirom density $\rho$, masses $M_P$ and $M_Q$, an surface areas $A$ and $4 A$, respectively. A spherical planet $R$ also has unfirom density $\rho$ and its mass is $\left(M_p+M_Q\right)$. The escape velocities from the planets $\mathrm{P}, \mathrm{Q}$ and R , are $\mathrm{V}_{\mathrm{p}}, \mathrm{V}_0$ and V respectivley. Then