A World of Wedges

Where else besides the kitchen can you find wedges? Let’s go on awedge huntand find out.

Check out most any garage or toolbox. Nails are wedges. So are thumbtacks and push pins. After these wedges are driven into a material, such as wood or cork, friction holds them in place. That’s how nails hold pieces of wood together. It’s also how your science report stays pinned to the bulletin board.

Lots of garden tools are made of wedges. These include the blades of shovels, hoes, and weeding toolspretty much anything designed to dig.

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

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

Some wedges are easy to see. You can see how a sculptor uses a chisel to break off bits of rock while creating a statue. But some tools have wedges hidden inside them. One of these tools is something you probably use every day. It’s on pants, jackets, and book bags. Can you guess what it is? It’s a zipper!

Closing a zipper is easy, thanks to wedges. 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.

Wedges on the Move

So far, most of the wedges you have read about cut through solid matter, like wood, soil, and food. But liquids and gases are matter, too. Do wedges cut through this matter? Sure, just look at the front of a boat. The wedge shape of the bow lets the boat slice through the water with ease.

Now consider the narrow front of cars, planes, and trains. The wedge shape makes it easier for these vehicles to push away all the air particles as they move. Then they can go faster and use less fuel.

Wedges are a great idea, but all we’re doing is following nature’s lead. Think of the sleek shape of dolphins and sharks. Their wedge shape gives them the speed they need to catch prey.

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?