Overview

This is the second in a series of posts looking at Simple Machines (Lever, Wedge, Inclined Plane, Pulley, Wheel and Axle, Screw). Becoming more aware of the Wedges, and other Simple Machines, in your early learning setting will make you more confident supporting STEM (Science, Technology, Engineering, and Math) play and answering children’s questions about how many everyday items work.

What’s A Wedge?

A wedge is an object with a pointed edge at one end and a wide edge at the opposite end. Wedges are commonly made of wood or metal but can be made of other materials as well. First made of stone, wedges are probably the first simple machines to be used by humans. The first wedges were probably used as weapons. Now wedges are part of everything from cookie cutters to garden rakes.

A Simple Machine is a mechanical device used to modify motion and force in order to perform work.¹

What Wedges Do

The job of a lot of Wedges is to split things apart. When Force is applied to a wedge’s blunt end, “it gets divided into output forces that are exerted in opposite directions, perpendicular to the input force.”²

Here’s an example. When a knife blade (a Wedge) is pressed downward (Input Force) through a banana, the banana is split (Output Force), resulting in yummy slices of banana.

Wedges are everywhere! Even we humans are blessed with a face-full of wedges:

Most Wedges you encounter have attached handles that usually act as Levers. In the image below, the shovel (a Compound Machine made up of a Wedge and Lever) is being used to slice a pumpkin.

Because of their shape, Wedges are great tools for slicing bananas, chewing food, and splitting wood. A Wedge’s narrow pointy end splits an object in twain with much less effort than a blunt object. For example, a log struck with a sledge hammer bounces away unharmed:

While the same log struck by an axe (a Wedge) splits in twain.

But Wait, There’s More!

Wedges cut and split, but they do other things as well. Here’s a list of all the tasks they preform:

• They cut (knives or teeth)
• They split (axes or cookie cutters)
• They tighten and hold (doorstops or zippers)
• They hold together (nails or pins)
• They scrape ( snow plows or paint scrapers)