ASTR 101 Lecture 14: Astronomy Chapter 4: Making Sense of the Universe: Understanding Motion, Energy, and Gravity
12 Dec 2017
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Newtons 3 laws of motion: an object in motion stays in motion. An object moves at constant velocity unless a net force acts to change its speed or direction force = mass x acceleration. 2: every action has an equal and opposite reaction force. The universal law of gravity: every mass attracts every other mass, attraction is directly proportional to the product of their masses, attraction is inversely proportional to the square of the distance between their centres. Newtons law of gravity relate to kepler"s law. Kepler"s rer 2 laws apply to all orbiting objects, not just planets. Ellipses are not the only orbital paths. If a small object orbits a larger object and you measure the orbiting objects orbital period and average orbital distance. Then you can calculate the mass of the larger object. Objects continue at constant velocity because of conservation of momentum.
