Summary
Highlights
Some heavy loads are difficult or impossible to move without help. Simple machines are mechanical devices with few parts that reduce the force needed to accomplish a task. There are three types: the inclined plane, the lever, and the wheel. This video focuses on the inclined plane.
Two simple machines are derived from the inclined plane: the wedge and the screw. A wedge consists of two inclined planes placed against each other. It reduces the force required to separate objects, like a knife or an axe, or to separate two joined objects, like a flat-head screwdriver. It can also be used to level objects, like a wooden shim.
A screw is an inclined plane wrapped around an axis, forming a helix called a thread. Screws increase pressure between two objects or fasten them together. They can exert pressure, like a bolt and nut, or fix objects together using various types of conventional screws. They can also move liquid or solid substances, like a snow blower.
An inclined plane is a rigid, flat surface at an angle to the horizontal. It allows lifting or lowering loads by sliding them instead of lifting them directly. For example, moving a 5 Newton mass vertically requires 5 Newtons of force, but sliding it up an inclined plane might only require 3.5 Newtons.
For an inclined plane to be efficient, friction between the load and the plane must be minimized. Also, a lower slope requires less force but increases the distance covered. Examples in daily life include wheelchair ramps, moving ramps, and stairs.