Thursday, April 23, 2009

Orbiting Gravity.


I never realized until I read it a few months ago how things like a satellite stays in orbit , when I read about Isaac Newton's Cannonball Theory:
Then Newton realized that if he chose just the right velocity, the trajectory of the cannonball would curve at exactly the same rate the Earth (being spherical) curves, and therefore the cannonball would always stay the same height above the ground. In doing so, he balances the inertia of the cannonball (which makes it want to continue traveling in a straight line, and therefore away from the Earth) against the acceleration due to the Earth's gravity (which pulls the cannonball toward the center of the Earth).

In other words, a satellite is actually continually falling back towards the Earth, but is moving at such speed that it constantly falls along the curvature of the Earth. The actual formula Newton devised is

Am I the only one this wasn't explained to in 7th grade? Christ.

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