In the circuit you have to slow down to speed up

If you watch In science fiction movies, you’d think flying a spaceship would be just like driving a slightly more complicated car (or Winnebago in Space balls). And George Lucas gave us those galactic battles with pilots who look like they’re flying fighter jets on Earth.

Well, the bad news: the atmosphere is really different. In particular, the movement of a vehicle in Earth orbit is much more complicated than that. Maneuvers you might do with the plane sometimes backfire on the circuit.

To see what I mean, let’s first consider some basic physics and build ourselves a little model of orbital mechanics, and then I’ll have some interesting simulations of trying to maneuver the connection. Read more

Circular circuits

Imagine flying around the earth in a circular orbit. There are three big ideas of physics that we need to understand this kind of motion. first, Centrifugal acceleration. Recall that acceleration is a measure of the rate of change of speed of an object.

But speed is not just speed, speed is special direction– In other words, it is a vector. If an object moves in a circle, its direction is constantly changing, that is, it is constantly accelerating, even if its speed is constant!

The direction of this acceleration is towards the center of the circle. (“Centripetal” means center.) The magnitude of the acceleration depends on both the magnitudes of the velocity (v) i.e. speed and radius (r) circle. This gives the following equation:

Courtesy of Rhett Allen