Simple machines are basic devices that make work easier, usually by trading a small force over a long distance for a big force over a short distance. The total work done is the same, but the machine multiplies the force you can apply. Humans have used simple machines for thousands of years. The ancient Greeks identified six basic types, and almost every complicated machine you see today (cars, cranes, bicycles, electric drills, scissors) is built from combinations of these six.
- How manySix classic typesIdentified by ancient Greeks
- LeverA bar pivoted at a pointSeesaws, crowbars, scissors
- Wheel and axleWheel on a shaftCars, doorknobs, fans
- PulleyRope over a wheelCranes, flagpoles, blinds
- Inclined planeA slopeRamps, hills, stairs
- WedgeTwo slopes back to backKnives, axes, doorstops
- ScrewSlope wrapped in a spiralWood screws, jar lids, drills
What you will learn here
- The six simple machines: a quick tour of all of them.
- Lever: a bar that pivots.
- Wheel and axle: turning motion made easier.
- Pulley: lifting with a rope and wheel.
- Inclined plane: trading height for distance.
- Wedge: splitting with a sharp edge.
- Screw: a wrapped-up inclined plane.
Why it matters
Every machine ever invented (from the simplest bottle opener to the most complex robot) is made by combining simple machines. The pyramid builders used inclined planes and levers. Roman engineers built siege weapons from levers and pulleys. Medieval millers harnessed water and wind with wheels and axles. Modern factories combine all six in clever ways. Understanding simple machines is the first step to understanding how anything mechanical works.