In planetary motion the areal velocity of position vector of a planet depends on angular velocity $$\left( \omega \right)$$ and the distance of the planet from sun $$\left( r \right).$$ If so, the correct relation for areal velocity is
A.
$$\frac{{dA}}{{dt}} \propto \omega r$$
B.
$$\frac{{dA}}{{dt}} \propto {\omega ^2}r$$
C.
$$\frac{{dA}}{{dt}} \propto \omega {r^2}$$
D.
$$\frac{{dA}}{{dt}} \propto \sqrt {\omega r} $$
If $$g$$ is the acceleration due to gravity on the earth’s surface, the gain in the potential energy of an object of mass $$m$$ raised from the surface of the earth to a height equal to the radius $$R$$ of the earth, is-
A geo-stationary satellite orbits around the earth in a circular orbit of radius $$36,000 \,km.$$ Then, the time period of a spy satellite orbiting a few hundred km above the earth's surface $$\left( {{R_{earth}} = 6400\,km} \right)$$ will approximately be-