Simple machines
Six machines that changed civilisation. Drag the fulcrum, add pulleys, tilt the ramp — watch force multiply and energy stay conserved. From Archimedes to modern engineering, the physics of mechanical advantage.
MA = Fₚ₠ᵗ / Fᵢₙ Workᵢₙ = Workₚ₠ᵗ F × d = constant
Mechanical advantage
A simple machine trades force for distance. The mechanical advantage (MA) is the ratio of output force to input force. A lever with MA = 3 triples the force you apply — but you must move your end three times as far. Energy is conserved: work in always equals work out (minus friction losses).
The six classical machines
The lever amplifies force around a fulcrum. The pulley redirects and multiplies force using ropes and wheels. The inclined plane trades a longer path for less force against gravity. The wedge converts axial force into lateral splitting force. The screw converts rotational force into linear advance. The wheel and axle amplifies torque through radius ratio.
Energy conservation
No simple machine creates energy. Fᵢₙ × dᵢₙ = Fₚ₠ᵗ × dₚ₠ᵗ. This is the work-energy principle: what you gain in force, you lose in distance. In practice, friction steals some energy as heat, so real machines always have efficiency less than 100%.
Archimedes
“Give me a lever long enough and a fulcrum on which to place it, and I shall move the world.” Archimedes understood that mechanical advantage is limited only by geometry. Every complex machine — from bicycles to cranes — is ultimately a combination of these six simple machines.
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