Newton's laws of motion and gravity
- Author:
- Roman Hašek
Isaac Newton (1643–1727), English physicists and mathematician, in 1687 in Philosophicae Naturalis PrincipiaMathematica formulated laws of motion and the law of gravity (an inverse–square law of gravity) and developed a mathematical method that enabled him to derive Kepler’s laws as consequences of his (Newton’s) laws (What is interesting is that despite this he provide geometric proof of Kepler’s laws in Principia).
From Newton's laws of motion and gravity we are particularly interested in the following three assertions:
- An object keeps its state of motion (rest or a motion at a constant speed in the same direction) unless an external force is impressed on it (1st law, the law of inertia).
- The change in motion is proportional to the motive force impressed; it is made in the direction of the straight line in which that force is impressed (2nd law).
- The force of gravity diminishes as R-2, where R is the distance from a planet to the Sun (the inverse square of the distance nature of gravity).