Gravitation or gravity is a naturally occurring phenomenon or a force which exists among all material objects in the universe.
Newton's Law of Gravitation: The newton's law of universal gravitation states that the gravitational force (F) of attraction between two substance of masses m1 and m2, separated by the distance (r) is
F = Gm1m2/r2
Kepler's Law of Planetary Motion
Kepler's laws of planetary motion state that:
- All planets move in elliptical orbits with the Sun at one of the focal points.
- The radius vector drawn from the Sun to a planet sweeps out equal areas in equal time intervals. This follows from the fact that the force of gravitation on the planet is central and hence angular momentum is conserved.
- The square of the orbital period of a planet is proportional to the cube of the semi-major axis of the elliptical orbit of the planet.