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Throughout history, people have developed several simple machines to make work easier. The best known of these are the so-called “six simple machines”: axle, lever, ramp, pulley, screw, and wedge, although the last three are really just extensions or combinations of the first three. 3. According to the Encyclopædia Britannica.
According to Boston University, since work is defined as the force acting on an object in the direction of motion, machines make work easier by performing one or more of the following functions:
Simple machines are devices with no or few moving parts that make work easier. According to the University of Colorado at Boulder, many of today’s complex instruments are simply combinations of half a dozen simple mechanisms or more complex shapes. For example, we can attach a long handle to an axle to make a winch, or use a pulley to pull a load up a ramp. Although these machines seem simple, they continue to provide us with the means to do many things that we could not do without them.
The wheel is considered one of the most important inventions in world history. As Live Science previously reported, “prior to the invention of the wheel in 3500 BC, humans were severely limited in the number and distance of objects they could transport over land.” Wheeled carts facilitated agriculture and trade by allowing goods to be transported to and from markets, and eased the burden of people traveling long distances.
Wheels greatly reduce the friction that objects experience when moving on a surface. According to the University of Tennessee, “If you put a file cabinet on a small cart with wheels, you can greatly reduce the effort required to move the file cabinet at a constant speed.”
In his book “Ancient Science: Prehistory – 500 AD” Charlie Samuels writes: “In some parts of the world, heavy objects such as rocks and ships were moved by wooden rollers. replaced.” front. This is the first step in the evolution of the wheel.
However, the big innovation was the mounting of the wheels on the axle. The wheels may be fixed on an axle supported by bearings, or may be free to rotate around the axle. This led to the development of mounds, horse-drawn carts and chariots. According to Samuels, archaeologists use the development of a spinning wheel as a sign of a relatively advanced civilization. The earliest evidence of wheels on axles dates back to the Sumerians in 3200 BC. The Chinese independently invented the wheel in 2800 BC.
In addition to reducing friction, the axle acts as a force multiplier. If a wheel is attached to an axle and a force is used to turn the wheel, the rotating force or torque on the axle is much greater than the force applied to the rim. Alternatively, a long handle can be attached to the rod for a similar effect.
All other five machines help people increase and/or change the force applied to objects. In Moving Large Objects, Janet L. Kolodner and her co-authors write: “A machine provides a mechanical advantage to help move an object. Mechanical advantage is a compromise between strength and distance.” In the following discussion of simple machines that increase the force applied to the input, we will ignore friction because in most cases it is very small compared to the input and output forces acting.
When a force is applied at a distance, work is done. Mathematically, this is expressed as W = F × D. For example, in order to lift an object, we must do work to overcome gravity and lift the object up. To lift an object twice as heavy requires twice as much force to lift the same distance. According to an Auburn University study, it takes twice as much work to lift the same object twice the distance. As the math shows, the main advantage of machines is that they allow us to do the same amount of work with less force over a greater distance.
“Give me a lever and a point of support, and I will move the world,” this boastful statement is attributed to the third-century Greek philosopher, mathematician, and inventor Archimedes. While this may be an exaggeration, it does express the power of leverage, at least figuratively, to move the world.
The genius of Archimedes was that he realized that it was possible to use leverage to exchange force and distance in order to accomplish the same volume or work. His law of leverage states that “size is in equilibrium at a distance inversely proportional to its weight,” according to the fictional book Archimedes in the 21st Century by Chris Rorres of New York University.
A lever consists of a long beam and a fulcrum or hinge. The mechanical advantage of a lever depends on the ratio of the lengths of the beams on either side of the fulcrum.
For example, let’s say we want to lift an object that weighs 100 pounds. (45 kg) weight 2 feet (61 cm) above ground. We can apply 100 pounds of force. The force acting on the weight moves up a distance of 2 feet, and we do work of 200 lb-ft (271 Newton meters). However, if we use a 30 ft (9 m) long lever with one end under the load and a 1 ft (30.5 cm) fulcrum located under the beam 10 ft (3 m) from the load, we will only get the other end pushing. . down 50 pounds. (23 kg) strength for lifting heavy objects. However, we had to lower the end of the arm 4 feet (1.2 m) to raise the weight 2 feet. We compromised by doubling the distance the lever travels, but halving the effort required to do the same job.
A slope is simply a flat surface raised at an angle, like a slope. According to Bob Williams, professor of mechanical engineering at Russ College of Engineering and Technology, ramps are a way to lift loads that are too heavy to lift vertically. The angle (steepness of the slope) determines how much force is required to lift the load. The steeper the ramp, the more effort required. This means that if we lift 100 pounds. By rolling it down a 4-foot ramp and weighing 2 feet, we halve the force required and double the distance it has to travel. If we use an 8 foot (2.4 m) ramp, we can reduce the required force to 25 pounds. (11.3 kg).
If we want to lift the same 100 pounds. With the rope load, we can attach the pulley to the beam above the load. This allows us to pull the rope down instead of up, but it still requires 100 pounds. force. However, if we use two pulleys – one attached to the suspension beam and the other to the load – we attach one end of the rope to the beam, thread it through the pulley on the load, and then through the pulley, we only need to pull the rope with a force of 50 pounds . Strength to lift weights, although we had to pull the rope 4 feet to lift the weight 2 feet. Again, we trade an increase in distance for a decrease in power.
If we want to use less force over a longer distance, we can use a chain hoist. According to the University of South Carolina course materials, “a pulley block is a combination of pulleys that reduces the amount of force needed to lift an object. The tradeoff is that the pulley block needs longer ropes to move something the same distance. .”
Despite their simplicity, pulleys are still used in modern new machines. For example, the Hangprinter, a 3D printer that can print furniture-sized objects, uses a system of wires and computer-controlled pulleys attached to walls, floors, and ceilings.
“A screw is essentially a long ramp wrapped around a shaft, so its mechanical advantage can be achieved in the same way as ramps,” says Georgia State University. Many devices use screws, which exert much more force than rotation screw. Such devices include locksmith vise and lug nuts on car wheels. They derive mechanical advantage not only from the propeller itself, but in many cases also from the leverage of the long handle used to turn the propeller.
According to the New Mexico Institute of Mining and Technology, “The wedges move on an inclined plane driven by the weight to lift or inside the weight to separate or separate.” otherwise: the main function of the wedge is to redirect the input force. For example, if we want to split a log, we can use a sledgehammer to push a wedge into the end of the log with great force, and the wedge will redirect that force outward, causing the wood to split. Another example is a door stop, the force used to push it under the edge of the door is transferred down, creating friction that prevents it from sliding across the floor.
John H. Lienhard, professor emeritus of mechanical engineering and history at the University of Houston, “Reconsiders the invention of the wheel.” Visit the Center for Science and Industry in Columbus, Ohio for interactive explanations of simple mechanisms. HyperPhysics (a website hosted by Georgia State University) also includes a graphical explanation of six simple mechanisms.
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Post time: Aug-21-2023