<Tr> <Td> <Ul> <Li> </Li> <Li> </Li> <Li> </Li> </Ul> </Td> </Tr> <Ul> <Li> </Li> <Li> </Li> <Li> </Li> </Ul> <P> Newton's law of universal gravitation states that a particle attracts every other particle in the universe using a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers . This is a general physical law derived from empirical observations by what Isaac Newton called inductive reasoning . It is a part of classical mechanics and was formulated in Newton's work Philosophiæ Naturalis Principia Mathematica ("the Principia"), first published on 5 July 1686 . When Newton's book was presented in 1686 to the Royal Society, Robert Hooke made a claim that Newton had obtained the inverse square law from him . </P> <P> In today's language, the law states: Every point mass attracts every single other point mass by a force pointing along the line intersecting both points . The force is proportional to the product of the two masses and inversely proportional to the square of the distance between them . The first test of Newton's theory of gravitation between masses in the laboratory was the Cavendish experiment conducted by the British scientist Henry Cavendish in 1798 . It took place 111 years after the publication of Newton's Principia and approximately 71 years after his death . </P>

Newton's law of universal gravitation and the second law of motion