The axle helps the wheel turn. W. Wheel and axles make things easier to move. A wedge is two inclined planes placed back to back. When a man hammers from the top, the wood is split apart from side to side. A nail is a wedge.
Many people use a wedge to force things apart.
A screw is an inclined plane wrapped around a nail. Each time a screw is given a complete turn, it advances into a piece of wood or lifts an object only as far as the distance between its threads. A screw can raise and lower things. A screw can hold things together. A screw can cut.