Wedge

A wedge is a special kind of tool that is shaped like a triangle. It is one of the six simple machines that help make work easier. Because of its shape, a wedge can be used to push things apart, lift heavy objects, or keep things in place.

The way a wedge works is by turning the force you put on its wide, flat end into forces that push out on the slanted sides. This helps it do tasks that would be hard without it.

One important part of understanding how a wedge works is its mechanical advantage, which tells us how much it can multiply the force we apply. This is figured out by comparing the length of the sloping side to the width of the wedge.

History

Wedges have been used for thousands of years. The earliest wedges were made from simple stone, like the hand axe. These tools helped people split materials apart by turning a pushing force into a splitting force.

Ancient Egyptians used bronze wedges in their stone quarries, and wooden wedges that expanded when wet were also common. Indigenous peoples in the Americas used wedges made from antler to work wood for canoes and homes.

Uses of a wedge

Wedges are used to lift heavy objects by sliding under them. As the wedge moves under the object, the object moves up the sloped side of the wedge. This helps lift the weight of the object.

Wedges can also be used to separate objects, like blocks of cut stone. Tools such as splitting mauls and splitting wedges help split wood. Narrow wedges, called gibs, are used to finely adjust the distance between objects in machines. The tips of forks and nails act like wedges because they split and separate materials they push into.

Blades and wedges

A blade is like two inclined planes that meet at an edge. When you push this edge into something, it helps separate materials by spreading the force out in two directions.

The first blades people used were made from flint stone, which helped them cut through animal tissue, like meat. Later, using iron and other metals, people made knives. These knives made cutting much easier than just pulling things apart by hand. Other tools that work like blades include plows for soil, scissors for fabric, axes for wood, and chisels for shaping wood.

Wedges, saws, and chisels are great for separating thick, hard materials like wood, stone, and metal. They do this with less force, less waste, and more precision than just crushing the material. Drill bits are another example of wedges. Their sharp edges spin and cut into materials, creating holes while also helping to remove the cut pieces.

Examples for holding objects faster

Wedges can help keep things in place. For example, they are used in engine parts like poppet valves, bicycle parts such as stems and bottom brackets, and even doors. A door wedge stops a door from closing by creating friction between the door, the wedge, and the floor.

Mechanical advantage

The mechanical advantage of a wedge can be found by dividing the height of the wedge by its width.

The narrower the angle of a wedge, the more it can help lift or move things. If the angle is too small, however, the wedge can get stuck, especially in materials like wood. This is why tools like splitting mauls have wider angles than axes.