Gravitation- Notes

Kepler’s laws
Ptolemy formulated the geocentric theory, while Copernicus formulated the heliocentric theory.
Kepler’s three laws of planetary motion are:
1) The Law of orbits
2) The law of areas
3) The law of periods
The law of orbits states that all the planets revolve in elliptical orbits with the sun at one of the foci of the eclipse.
The law of areas state that the line joining the sun and a planet sweeps equal areas in equal time of intervals.
The law of periods state that the square of the time period of a planet is directly proportional to the cube of the semi-major axis of its elliptical.

Universal law of gravitation
The forces of attraction between any two bodies applies to all the bodies in the future.
The moon revolving around the earth is under the action of centripetal force.
The magnitude of gravitational force varies with the:
• Distance of the object from the earth