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Wedge

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A wedge is a fundamental tool used to manipulate the world around us. It is classified as one of the six simple machines.

Wedge-diagram
Wedge-diagram

Geometrically, a wedge is a portable inclined plane with a triangular shape. It serves several distinct purposes in mechanics. A wedge can separate two objects or portions of a single object. It can also lift an object upward or hold an object firmly in place. Because it can multiply force, the wedge is essential for many human tasks.

The mechanism of a wedge relies on the conversion of energy and force. A user applies a force to the blunt, flat end of the tool. This energy is transported toward the sharp, pointy end. The wedge transforms this lateral movement into a transverse splitting force. Specifically, it converts the input force into two opposing forces that are perpendicular, or normal, to the inclined surfaces.

Wedge-diagram
Wedge-diagram

This process allows the wedge to overcome the resistance of a material. By concentrating energy at a tiny point, the wedge can split items with much higher precision than crushing them would allow.

Mechanical advantage is a key concept used to describe how well a wedge works. This advantage is the ratio of the input speed to the output speed. It can also be calculated by the ratio of the length of the wedge's slope to its width.

Wedge-diagram
Wedge-diagram

Another way to find this is by dividing the height of the wedge by its width. The angle of the tip, known as the tip angle, is also vital. A narrow wedge with a small angle provides a much greater mechanical advantage. While a short, wide wedge might complete a task faster, it requires much more force to operate. Conversely, a long, narrow wedge makes the work easier by amplifying the force.

History shows that humans have utilized wedges for thousands of years. The exact origin of the wedge is unknown, but its earliest forms were made of stone. One early example is the hand axe, created by chipping stone like flint to form a bifacial edge.

Flint hand axe
Flint hand axe

In ancient Egyptian quarries, workers used bronze wedges to break large blocks of stone for construction. Some cultures even used wooden wedges for this purpose. They would saturate the wood with water so that it would swell and crack the stone. Indigenous peoples in the Americas also used antler wedges to work wood for canoes and dwellings.

There are many specialized types of wedges used in different industries. A very narrow wedge with a long taper is called a gib. These are used to make fine adjustments in machine tools.

Wedge-1
Wedge-1

Blades are considered compound inclined planes. A blade consists of two inclined planes meeting at a single edge. This design is seen in knives, which allow humans to cut meat and fibers with less force than pulling by hand. Other examples include axes for wood, plows for soil, and chisels for woodworking. Even drill bits use sharpened edges at opposing angles to create holes in solids.

Beyond splitting, wedges are excellent at holding objects in place through friction. A common example is the door wedge, or doorstop. It works because of the friction generated between the door, the wedge, and the floor.

Wedge-1
Wedge-1

This same principle allows wedges to hold engine parts, such as poppet valves, or bicycle parts like stems in place. However, a wedge can also "bind" or get stuck. This happens if the angle is too narrow relative to the friction of the material. In elastic materials like wood, a narrow wedge may bind more easily than a wide one.

The wedge connects to many different fields of science and engineering. It is a primary component in the study of mechanics and simple machines. From the smallest nail or fork tip to massive stone-splitting tools, the wedge is everywhere.

Wedge-1
Wedge-1

It demonstrates how geometry can be used to control physical forces. By understanding the relationship between angle, width, and force, humans can build everything from simple hand tools to complex machinery.

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Wedge-1.jpg
File:Flint hand axe.JPG
Flint hand axe.JPG
File:Wedge-diagram.svg
Wedge-diagram.svg
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