Two planets move around the sun. The periodic times and the mean radii of the orbits are $T_1, T_2$ and $r_1, r_2$ respectively. The ratio $T_1/T_2$ is equal to

The mean radius of the earth's orbit around the sun is $1.5 \times 10^{11} \ m$. The mean radius of the orbit of mercury around the sun is $6 \times 10^{10} \ m$. The mercury will rotate around the sun in

$A$ planet $(P_1)$ is moving around a star of mass $2M$ in an orbit of radius $R$. Another planet $(P_2)$ is moving around another star of mass $4M$ in an orbit of radius $2R$. The ratio of the time periods of revolution of $P_2$ and $P_1$ is . . . . . . .

If the distance between the earth and the sun becomes half its present value,the number of days in a year would have been

$A$ body revolves around the sun $27$ times faster than the earth. What is the ratio of their orbital radii?

Which of the following quantities does not depend upon the orbital radius of the satellite?