The unit of universal gravitational constant is :

If the distance between the Sun and Earth is doubled, then the duration of the year on earth will be :

[Given actual duration of the year $=\mathbf{T}$ ]

The value of universal gravitational constant was first determined by

Two spherical planets P and Q have the same uniform density $\rho$, and masses Mp and $\mathrm{MQ}_{\mathrm{Q}}$ and surface areas A and 4 A respectively. Another spherical planet $R$ also has the same uniform density $\rho$, and its mass is $\mathrm{Mp}+\mathrm{MQ}$. The escape velocities from these planets is