411 REFERENCE · Wikibooks
Modern Physics/Use of Conservation Laws
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(1) kepler's first law state that the planets describe eclipse of the sun as one focus.
(2) kepler's second law states that the line joining the sun and the planet sweeps out equal areas in equal time.
(3) kepler's third law states that the square s of the periods of revolution of the planets are proportional to the cube of their mean distances from the sun.