Simple Machines: Making Work Easier

Simple machines are clever shapes that make work easier. They do not give you extra strength — they change the way you have to push, so the job needs less effort from you.

Here are three of them, and every one is somewhere in your house right now.

Levers: Like a Seesaw

A lever is a stiff bar that turns around a fixed point. That point is called the fulcrum. Push down on one end and the other end goes up.

• A seesaw
• A wheelbarrow
• A bottle opener

Wheels and Axles: Rolling Along

A wheel turns around a rod through its middle called an axle. Dragging a heavy box across the floor is hard because the whole bottom of the box rubs. Put it on wheels and only a tiny patch touches the ground at a time.

• A bicycle
• A car
• A doorknob

Inclined Planes: Going Up

An inclined plane is just a tilted flat surface — a ramp. Walking a heavy thing up a slope takes less effort than lifting it straight up, because you spread the work over a longer distance.

• A ramp into a building
• A slide at the playground
• A screw, which is an inclined plane wrapped around a rod

Sort These Into Their Machines

Every object below is one of the three machines you just read about. Wheel is short for wheel and axle, and Ramp for inclined plane.

A wheelbarrow is a tricky one. It has a wheel, but the part that does the lifting is the long handles turning around that wheel — so it counts as a lever. Plenty of real machines are two simple machines stuck together.

Go and Find Some

Walk around one room and count the simple machines in it. Door handles, taps, scissors, a stapler, the ramp at a shop entrance, the wheels on a chair. Most people are surprised how many there are once they start looking.