A wedge is often used to cut material by applying force to flat end. The angled end then splits the object being struck in two. For example, when an axe strikes a log and the log splits into two halves. Real Life examples of tools that use a wedge.
- Apr 04, 2020 Shovels, scissors, axes, pick axes, saws and ice picks are all examples of wedges that push things apart. Other wedges that drive into materials and force them to split are chisels, jackhammers, bulldozers, snow plows, horse plows, airplane wings and bows of boats or ships.
- A fork, a shovel, teeth — they’re all examples of the wedge, a triangle-shaped tool with at least one slanted side. One of the earliest simple machines, wedges help you lift or separate objects with less effort. In Wedge It, you can use one kind of wedge (your hands and feet) to scamper up a wedge-shaped climbing wall.
- Dump truck ladder roller coaster A wedge is a type of simple machine.A wedge is two inclined planes that are back to back.The difference between an inclined plane is that it does its work by staying still, while a wedge moves.
- Some examples of wedges that are used for separating might be a shovel, a knife, an axe, a pick axe, a saw, a needle, scissors, or an ice pick. But wedges can also hold things together as in the case of a staple, push pins, tack, nail, doorstop, or a shim.
Once upon a time a person needed to move something heavy. He or she picked up a long stick and stuck it under the edge of the heavy object and then pushed down on the other end of the stick. And the first simple machine was invented. Simple machines are just that. The simplest form of using one thing to accomplish something faster or better. A tool. They were the first ones created and we still use them today.
There are 6 basic simple machines; the lever, the wheel and axle, the inclined plane, the wedge, the pulley, and the screw. Several of these simple machines are related to each other. But, each has a specific purpose in the world of doing work.
But what is work? Work is the amount of energy necessary to move an object. The further you move it, the more work is required. Work is measured in Newtons. More about that later. First let's look at each of the 6 simple machines in detail.
A wedge is a triangular shaped tool, and is a portable inclined plane, and one of the six simple machines. It can be used to separate two objects or portions of an object, lift up an object, or hold an object in place. It functions by converting a force applied to its blunt end into forces perpendicular (normal) to its inclined surfaces. The mechanical advantage of a wedge is given by the ratio of the length of its slope to its width.[1][2] Although a short wedge with a wide angle may do a job faster, it requires more force than a long wedge with a narrow angle.
The force is applied on a flat, broad surface. This energy is transported to the pointy, sharp end of the wedge, hence the force is transported.
The wedge simply transports energy and collects it to the pointy end, consequently breaking the item. In this way, much pressure is put on a thin area.
History[edit]
Wedges have existed for thousands of years. They were first made of simple stone. Perhaps the first example of a wedge is the hand axe (see also biface and Olorgesailie), which is made by chipping stone, generally flint, to form a bifacial edge, or wedge. A wedge is a simple machine that transforms lateral force and movement of the tool into a transverse splitting force and movement of the workpiece. The available power is limited by the effort of the person using the tool, but because power is the product of force and movement, the wedge amplifies the force by reducing the movement. This amplification, or mechanical advantage is the ratio of the input speed to output speed. For a wedge this is given by 1/tanα, where α is the tip angle. The faces of a wedge are modeled as straight lines to form a sliding or prismatic joint.
The origin of the wedge is not known. In ancient Egyptianquarries, bronze wedges were used to break away blocks of stone used in construction. Wooden wedges that swelled after being saturated with water, were also used. Some indigenous peoples of the Americas used antler wedges for splitting and working wood to make canoes, dwellings and other objects.
Use of a wedge[edit]
Wedges are used to lift heavy objects, separating them from the surface upon which they rest.[3]
Consider a block that is to be lifted by a wedge. As the wedge slides under the block, the block slides up the sloped side of a wedge. This lifts the weight FB of the block. The horizontal force FA needed to lift the block is obtained by considering the velocity of the wedge vA and the velocity of the block vB. If we assume the wedge does not dissipate or store energy, then the power into the wedge equals the power out.
or
The velocity of the block is related to the velocity of the wedge by the slope of the side of the wedge. If the angle of the wedge is α then
which means that the mechanical advantage
Thus, the smaller the angle α the greater the ratio of the lifting force to the applied force on the wedge. This is the mechanical advantage of the wedge. This formula for mechanical advantage applies to cutting edges and splitting operations as well as to lifting.
They can also be used to separate objects, such as blocks of cut stone. Splitting mauls and splitting wedges are used to split wood along the grain. A narrow wedge with a relatively long taper used to finely adjust the distance between objects is called a shim, and is commonly used in carpentry.
The tips of forks and nails are also wedges, as they split and separate the material into which they are pushed or driven; the shafts may then hold fast due to friction.
Blades and wedges[edit]
The blade is a compound inclined plane, consisting of two inclined planes placed so that the planes meet at one edge. When the edge where the two planes meet is pushed into a solid or fluid substance it overcomes the resistance of materials to separate by transferring the force exerted against the material into two opposing forces normal to the faces of the blade.
The blade's first known use by humans was the sharp edge of a flint stone that was used to cleave or split animal tissue, e.g. cutting meat. The use of iron or other metals led to the development of knives for those kinds of tasks. The blade of the knife allowed humans to cut meat, fibers, and other plant and animal materials with much less force than it would take to tear them apart by simply pulling with their hands. Other examples are plows, which separate soil particles, scissors which separate fabric, axes which separate wood fibers, and chisels and planes which separate wood.
Wedges, saws and chisels can separate thick and hard materials, such as wood, solid stone and hard metals and they do so with much less force, waste of material, and with more precision, than crushing, which is the application of the same force over a wider area of the material to be separated.
Other examples of wedges are found in drill bits, which produce circular holes in solids. The two edges of a drill bit are sharpened, at opposing angles, into a point and that edge is wound around the shaft of the drill bit. When the drill bit spins on its axis of rotation, the wedges are forced into the material to be separated. The resulting cut in the material is in the direction of rotation of the drill bit while the helical shape of a bit allows the removal of the cut material.
Examples for holding objects faster[edit]
Wedges can also be used to hold objects in place, such as engine parts (poppet valves), bicycle parts (stems and eccentricbottom brackets), and doors. A wedge-type door stop (door wedge) functions largely because of the friction generated between the bottom of the door and the wedge, and the wedge and the floor (or other surface).
Mechanical advantage[edit]
The mechanical advantage or MA of a wedge can be calculated by dividing the height of the wedge by the wedge's width:[1]
The more acute, or narrow, the angle of a wedge, the greater the ratio of the length of its slope to its width, and thus the more mechanical advantage it will yield.[2]
A wedge will bind when the wedge included angle is less than the arctangent of the coefficient of friction between the wedge and the material. Therefore, in an elastic material such as wood, friction may bind a narrow wedge more easily than a wide one. This is why the head of a splitting maul has a much wider angle than that of an axe.
See also[edit]
- Splitting maul and splitting wedges
References[edit]
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- ^ abBowser, Edward Albert (1920), An elementary treatise on analytic mechanics: with numerous examples (25th ed.), D. Van Nostrand Company, pp. 202–203.
- ^ abMcGraw-Hill Concise Encyclopedia of Science & Technology, Third Ed., Sybil P. Parker, ed., McGraw-Hill, Inc., 1992, p. 2041.
- ^J. M. McCarthy and Leo Joskowitz, “Kinematic Synthesis,” Formal Engineering Design Synthesis, (J. Cagan and E. Antonson, eds.), Cambridge Univ. Press, 2002.
