ASTR 101 Lecture Notes - Lecture 5: Tidal Acceleration, Tidal Locking, Electromagnetic Spectrum
30 Oct 2017
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How do gravity and energy together allow us to understand orbits: total orbit energy (gravitational and kinetic) stays constant if there is no external force, orbits cannot change simultaneously, total orbit energy stays constant. Changing an orbit: so what can make an object gain or lose orbital energy, friction or atmospheric drag, a gravitational encounter. How does gravity cause tides: moons gravity pulls harder on near side of earth than on far side, difference in moons gravitational pull stretches earth. Attraction is directly proportional to the product of their masses. Attraction is inversely proportional to the square of the distance between their centers. Tides and phases: the sun also has a small tidal effect on earth, size of tides thus depends on phase of moon. Tidal friction: tidal friction gradually slows earth"s rotation ( and makes the moon get farther from earth, the moon once orbited faster (or slower) tidal friction caused it to lock in synchronous rotation.
