ASTRO-110 Lecture Notes - Lecture 24: Inverse-Square Law, Escape Velocity, Electromagnetic Spectrum
9 Oct 2020
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Document Summary
The basic law that describes how gravity works is the universal law of gravitation. Following an inverse square law: doubling the distance weakens the force of gravity by 4. Keplers laws are consequences of the laws of motion and the universal law of gravitation. Kepler"s first 2 laws apply to all orbiting objects. Ellipses are not the only possible orbital paths. Bound orbits: orbits in which objects go around another object over and over. Unbound orbits: paths that bring an object close to another object just once. Newton also generalized keplers 3rd law to allow us to calculate the masses of distant objects. Orbital energy: the sum of its kinetic and gravitational potential energies stays the same. Orbits cannot change spontaneously an objects orbit can change only if it gains or loses orbital energy. Gravitational encounter: when objects pass near enough to feel the effects of the others gravity.
