Levers and pulleys are two types of simple machines that allow people to use less energy when performing work. A simple lever is a long pole or platform used to lift an object. In a simple pulley system, a rope looped around a wheel is used to raise and lower objects.
Levers are present in everyday objects, such as door handles, bottle openers, seesaws and light switches. In each case, the lever moves back and forth on a pivot point, known as a fulcrum, which could be a simple rock beneath a board or a more complex support frame. The fulcrum is positioned between the object and the point where force is applied; relocating it changes the effectiveness of the lever. For example, moving the fulcrum closer to the object increases how high the object can be lifted.
Pulleys incorporate another simple machine: the wheel and axle. In this simple system, a wheel rotates on a central guide pole, or axle, and a rope helps to redirect the force of energy. Instead of using excess energy to lift bulky cargo straight up, the person pulls downward on the rope, and the simple machine does the heavy lifting. Flagpoles, window blinds and elevator cars all require pulley systems to function.