Fire thrusters using Arrow keys. Experiment with Gravity Strength and Planet Mass. Additional Controls: Trace orbit with pen [u]p [d]own [c]lear. [g]row or [s]hrink the size (not mass) of the planet.
This is a simulation of Isaac Newton's laws: F = ma = GMm / d^2 The motion (velocity) comes from the acceleration 'a', which depends on distance 'd' from the center and is always towards it. The program computes it in 2D space using small time steps. Strangely, the mass 'm' of the satellite does not affect the orbit as it is on both sides! (But why inertial mass = gravitational mass?) The three laws of motion were first compiled by Isaac Newton in his Philosophiæ Naturalis Principia Mathematica (Mathematical Principles of Natural Philosophy), first published in 1687. Newton showed that these laws of motion, combined with his law of universal gravitation, explained Kepler's laws of planetary motion. Gravity is so weak that you only notice it with massive objects like planets. Actual value of G = 0.0000000000667384 (SI units).
