The physics behind this last point is called the "law of the lever," and a good way to think about it is to consider a seesaw. If the pivot sits in the middle of the seesaw, then each end of the board moves the same total distance up or down, and each end moves through the air at the same speed (they travel the same distance in the same amount of time). But slide the pivot closer to one end of the board, and two things happen. The distance traveled by the two ends begins to differ, since the long end travels a more dramatic arc than the shorter end. And the speeds of the ends of the board diverge. Both ends of the seesaw complete their respective arcs in the same span of time (presuming that the board doesn't bend). But the long end travels farther than the short one, which means that the long end also travels faster than the short end of the board. The farther an object like a tooth sits from the hinge of a lever, the faster it moves when that lever rotates.

Emlen, Douglas J, Animal Weapons_ The Evoluti…, loc. 124