Simple Machines That Help Us
A primary physics lesson on the six simple machines: levers, pulleys, wheels, inclined planes, wedges and screws, with everyday examples and an easy experiment.
Key takeaways
- Simple machines make work easier by changing the size or direction of a force.
- The six simple machines are the lever, wheel and axle, pulley, inclined plane, wedge, and screw.
- Machines do not give you free energy — they trade a smaller force for a longer distance.
What is a simple machine?
A simple machine is a tool with few or no moving parts that makes work easier. In physics, work means using a force to move something.
A simple machine cannot make energy from nothing. Instead, it can:
- change the size of a force (a small push does a big job), or
- change the direction of a force (pull down to lift something up).
There are six simple machines. Let's meet them all.
1. The lever
A lever is a stiff bar that turns on a point called the fulcrum. Push down on one end, and the other end lifts a load. A seesaw, a crowbar, and even a bottle opener are levers.
2. The wheel and axle
A wheel is joined to a rod called an axle. Turning the wheel turns the axle, which helps things roll instead of drag. Car wheels, doorknobs, and steering wheels all use this.
3. The pulley
A pulley is a wheel with a rope or chain over it. Pull the rope down, and the load goes up. That changes the direction of your force. Flagpoles and cranes use pulleys.
4. The inclined plane
An inclined plane is a ramp — a flat, slanted surface. Pushing a heavy box up a ramp is easier than lifting it straight up. You use less force, but you push over a longer distance.
5. The wedge
A wedge is like two inclined planes back to back. It is thick at one end and thin at the other. A knife, an axe, and your front teeth are wedges that cut and split things.
6. The screw
A screw is an inclined plane wrapped around a pole in a spiral. Turning it pushes it deep into wood or holds things tight. Jar lids and light-bulb bases are screws too.
The big trade-off
Machines follow a fair rule: what you save in force, you pay back in distance. A ramp lets you use half the force, but you must push twice as far. Nothing is truly free — the energy still has to come from you.
Try it yourself! 🧪
Build a lever with a ruler and a pencil.
- Lay a pencil flat on a table — that is your fulcrum.
- Rest a ruler across it like a seesaw.
- Put a small coin on one end. Press the other end down to flip the coin up!
- Now slide the pencil closer to the coin. Notice it is easier to lift. You changed the lever's power.
Simple machines change forces, and forces are all about motion. To go deeper, read about Newton's laws of motion.
Quick quiz
Test yourself and earn XP
What does a simple machine do?
Simple machines make work easier by changing how much force you need or which way it points.
A seesaw is an example of which simple machine?
A seesaw is a lever. It balances on a point called the fulcrum.
A ramp that lets you push a heavy box up instead of lifting it is a…
A ramp is an inclined plane. You push with less force, but over a longer distance.
Which machine is really an inclined plane wrapped around a pole?
A screw is an inclined plane wrapped into a spiral, which is why it grips so well.
FAQ
No. A machine can reduce the force you need, but you must move it a longer distance. The total work stays about the same.
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