Today: Good Gravity!

17 Sep

Gravity, one of the most taken for granted aspects of Physics, everybody uses it, most don’t realise they do, some find it something to overcome, few ignore it.

So it’s pretty important then.

A challenge I got set when i was in 6th form was to show Newton’s Law of Gravitation:

F(g) = GMm/r^2

One thing that bugged me then – and was one of the reasons I initially couldn’t do it, was the fact you need TWO bodies to solve the problem.

Solving Gravity as a two body problem – Easy

Solving Gravity as a single body problem – Near Impossible, you could say that F=ma (where a = g) is a simplified equation explaining Gravity as a single body problem. However this equations explains the motion of a body in ANOTHER’s gravitational field.

Getting a bit more pedantic, you could even say that solving a single body program is never that – single body – going to smaller and smaller dimensions, even an atom, is made up of smaller ‘masses’. Although the electrostatic force is more dominent (or even forces within the nucleus).

So is there a single body problem? For any type of Force?

– Electric Charges move in magnetic & electric fields; but not their own. They move in another charges field, but also create their own.

This is the same for Gravity, Push and Pull forces – everything.

So what happens to a single proton in the vastness of space?

I’m not sure yet myself. But let’s put a point(less) mass there to have a look……


2 Responses to “Today: Good Gravity!”

  1. physicsoul 17/09/2010 at 22:44 #

    Hmmm… don’t think gravity exists in the case of singularity.

    • harriparf 17/09/2010 at 22:54 #

      Physicssoul – do you mean a singularity as in a blackhole? or as in a single body? 🙂

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