I knew going into this that a heavy object takes more force to break inertia. It also take more force to stop its momentum once it's moving. Therefor, to animating something heavy should have a lot of slow in and slow out, but once it is moving it should move fast. Besides animating a heavy bouncing ball, this is my first time actually putting it into practice. I experimented for a while before I got it, but I think it works.