A World of Wedges

Where else besides the kitchen can you find wedges? Let’s find out.

Look in any garage or toolbox. Nails are wedges. So are thumbtacks and pushpins. After these wedges are driven or pushed into a material, such as wood or cork, friction holds them in place. That’s how nails hold pieces of wood together. That’s how your paper stays pinned to the bulletin board.

Lots of garden tools are made of wedges. The blades of shovels and hoes, for example. Pretty much anything designed to dig is a wedge.

Snowplows are wedges that scrape snow off roads. The shape of the wedge allows the plow to reach under the snow and lift it off the road.

Some wedges are easy to see, like a chisel that breaks off bits of rock while creating a statue. Some wedges are hidden inside tools, like a zipper!

When you pull up on the zipper, small wedges inside the slider push the teeth together. When you pull down, another wedge separates the teeth, like a tiny axe splitting wood.

When you pull down on a zipper tab, a small wedge inside the slider pushes the teeth apart.

Wedges on the Move

So far, most of the wedges you have read about cut through solid things. They can cut through liquids and gases, too. Do wedges cut through water? Sure, just look at the front of a boat. The wedge shape of the bow lets the boat slice easily through the water.

Wedges can also push through air. The wedge-shape front of cars, planes, and trains push away the air as they move. Then they can go faster!

These wedges just follow nature’s lead. Many animals, such as dolphins, have sleek wedge shapes that helps them move swiftly.

Back at the Campsite

Now that you know something about wedges, think about some ways you might use this simple machine on a camping trip. Hint: What would you use to roast marshmallows?