The Essential Guide to Physics for Flash Games, Animation, and Simulations

Particle interactions and force fields

Whenever we've talked about forces so far in this book, we've thought of them as being exerted by particles on other particles. But there is another way to think of forces that are exerted at a distance—we can think of them as being due to force fields. This is a fairly subtle concept, so we'll take some time to explain things in the next couple of sections.

Interaction at a distance

In this chapter, we'll deal exclusively with forces that are exerted and felt at a distance; the interacting objects don't need to be in contact. Actually, at a fundamental level, all forces are like that, even contact forces. The difference is that contact forces are felt when two objects are very close together. Collisions ...