What is the best location to find tutorials on physics in game development?

I'm very new to game development (iPhone/iPad specifically, if that matters at all) and am having a tough time with working with the physics part of animation. Specifically I'm trying to give several balls (circular UIImageView or CG circles) physical properties (gravity, weight, friction, etc).

Are there any really good tutorials on getting started with physics in game development? The language of the tutorial really doesn't matter as the mechanics of the physical movement really don't change.