The wedge. Now, the wedge is surprising. You can think of it as an incline plane that moves. A wedge is shaped like two inclined planes back to back. It is used to multiply the force needed to penetrate very hard objects. The longer and thinner the wedge is, the less the effort force required to overcome the resistance force. The wedge moves the resistance apart from each other.

Hal's Hardware sells a lot of wedges. [CLINKS] [LAUGHS]

[MUSIC PLAYING]

Like nails, a chisel, a blade of a plow, axes. Sharpening decreases the thickness of the cutting edge. The sharper the edge the less effort needed to move through the object being cut.

A knife has a wedge, and a paper cutter, a can opener, even needles. We actually make wedges here when we make keys.

(SINGING CARNIVAL MUSIC)

Ha-ha! Look, lock-jaw. The edges of a key are a series of wedges. The wedges push up the pins inside the lock. When all the pins are the right height, you can turn the key and the lock will open.