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

If the radius of earth were to shrink by two percent, its mass remaining the same, the acceleration due to gravity on the earth's surface would