Many bouncing balls are also doable without knowing any actual physics. Balls overlap? Push them away from each other such that the next frame they'd no longer overlap. The result looks surprisingly acceptable.
And if you add some blur (I think in Flash this was just a property you can set) based on how fast the ball is moving, it somehow looks more satisfying still.
One of my favorite projects was a bouncing ball sim synced over the network. So you could mess with the balls in one window and it would update in the other too. I never added ball-on-ball action though...
And if you add some blur (I think in Flash this was just a property you can set) based on how fast the ball is moving, it somehow looks more satisfying still.