The 6 Simple Machines
A simple machine is a device that changes the direction or size of a force. There are 6 types:
- ⚙ Lever — a bar that pivots on a fulcrum (seesaw, crowbar)
- 🛧 Wheel & Axle — a wheel attached to a rod (car wheel, doorknob)
- 😄 Pulley — a rope over a wheel that changes force direction (flagpole, elevator)
- 🔽 Inclined Plane — a slanted surface that reduces effort needed (ramp, staircase)
- 🔨 Wedge — two inclined planes joined at a point (axe, knife, doorstop)
- 🪝 Screw — an inclined plane wrapped around a cylinder (screw, bolt)
💡Key Idea
Simple machines do NOT reduce the total work needed — they change HOW you apply force. A ramp lets you use less force over a greater distance to accomplish the same work.
The Lever
A lever has three parts: the effort (force you apply), the load (weight you're lifting), and the fulcrum (pivot point).
The lever rule: Effort × Effort Distance = Load × Load Distance
Moving the fulcrum closer to the load means you need less effort to lift it — that's mechanical advantage!