Various Types of Simple Machines

Description: A lever is a rigid object (such as a board or bar) that rests on a fulcrum (a pivot point). An object that a lever moves is called the load. The closer the load is to the fulcrum, the easier it is to move with the lever.

Description: An inclined plane is a simple machine that consists of a flat surface that is higher on one end than the other (its endpoints are at different heights).

Inclined planes are used to move an object to a lower or higher place with less force over a longer distance than would be needed to move the object vertically.

Description: A wheel and axle is a type of simple machine. The axle is a rod that goes through the wheel, which allows the wheel to turn. A wheel is akin to a lever that constantly rotates, and mechanical advantage (the factor by which a mechanism multiplies the force put into it) is gained because the distance the outside of the wheel travels is typically much greater than the distance the outside of the axle travels. The friction on the axle is overcome by the force on the outside of the wheel.

Description: A screw is a simple machine that consists of an inclined plane that winds around itself. (It is a helical inclined plane.) They can be used to raise and lower a load or to hold objects together. More threading increases the mechanical advantage of the screw.

Description: A wedge is a simple machine that consists of two inclined planes that meet at an edge. Wedges are used to push two objects apart or hold two objects together. A force applied to the back of the wedge (opposite the edge) generates a force on either side of the wedge perpendicular to the surfaces of the inclined planes.

Also known as: sheave, block

Description: A pulley is a simple machine that consists of a wheel that is looped over by a rope, cable, or belt. The pulley may have a groove between two flanges around its circumference for the rope, cable, or belt to ride in.

Type 1 pulleys have a fixed axle and are used to change the direction of an applied force without increasing mechanical advantage.

Type 2 pulleys have a free axle and are used to increase mechanical advantage.

A compound pulley is a system consisting of a combination of pulleys with both fixed and free axles.

Mechanical advantage is realized when a pulley system lessens the force required to move a load by requiring a longer pulling distance.