The motion of planets in the solar system is an example of the conservation of:

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

Give the contribution of Tycho Brahe on planetary motion.

The distance of Neptune and Saturn from the Sun is nearly $10^{13} \ m$ and $10^{12} \ m$ respectively. Assuming that they move in circular orbits,their periodic times will be in the ratio:

If $A$ is the areal velocity of a planet of mass $M$,its angular momentum is

Explain Kepler's first law (Law of Orbits) for planetary motion.