write the three laws given by kepler. how did they help newton to arrive at the inverse square law of gravity?
Answers
Kepler’s three laws of planetary motion can be stated as follows: (1) All planets move about the Sun in elliptical orbits, having the Sun as one of the foci. (2) A radius vector joining any planet to the Sun sweeps out equal areas in equal lengths of time. (3) The squares of the sidereal periods (of revolution) of the planets are directly proportional to the cubes of their mean distances from the Sun. Knowledge of these laws, especially the second (the law of areas), proved crucial to Sir Isaac Newton in 1684–85, when he formulated his famous law of gravitation between Earth and the Moon and between the Sun and the planets, postulated by him to have validity for all objects anywhere in the universe. Newton showed that the motion of bodies subject to central gravitational force need not always follow the elliptical orbits specified by the first law of Kepler but can take paths defined by other, open conic curves; the motion can be in parabolic or hyperbolic orbits, depending on the total energy of the body. Thus, an object of sufficient energy—e.g., a comet—can enter the solar system and leave again without returning. From Kepler’s second law, it may be observed further that the angular momentum of any planet about an axis through the Sun and perpendicular to the orbital plane is also unchanging.
Answer:
Explanation:
Kepler’s laws:
(i) Kepler’s first law : The orbit of a planet is an
ellipse with the Sun at one of the foci.
(ii) Kepler’s second law : The line joining the planet
and the Sun sweeps equal areas in equal intervals
of time.
(iii) Kepler’s third law: The square of its period of
revolution around the Sun is directly proportional
to the cube of the mean distance of a planet from
the Sun.