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Throughout history, people have developed several simple machines to make work easier. The most famous of these are the so-called “Six Simple Machines”: wheel and axle, lever, inclined plane, pulley, screw and wedge, although the last three are actually just an extension or combination of the first three. 3. According to the Encyclopedia Britannica.
According to Boston University, since work is defined as the force exerted on an object in the direction of motion, machines facilitate work by performing one or more of the following functions:
Simple machines are devices that have no or few moving parts to make work easier. According to the University of Colorado Boulder, many of today’s complex tools are simply combinations of six simple machines or more complex shapes. For example, we can install a long handle on a shaft to make a winch, or use a pulley to pull a load up a ramp. Although these machines may seem simple, they continue to provide us with the means to do many things that would not be possible without them.
The wheel is considered one of the most important inventions in world history. As Live Science previously reported: “Before the invention of the wheel in 3500 BC, people were severely limited in the number and distance they could transport overland.” Wheeled carts promoted agriculture and trade by allowing goods to be transported to and from markets, and also relieved people of the burden of traveling long distances.
Wheels significantly reduce the friction an object encounters when moving across a surface. “If you place the filing cabinet on a dolly with wheels, you can significantly reduce the force required to move the filing cabinet at a constant speed,” says the University of Tennessee.
In his book “Ancient Science: Prehistory – 500 AD.” e.” Charles Samuels writes: “In some parts of the world, heavy objects such as stones and ships were moved by wooden rollers. As the object moves forward, the rollers are removed from the rear and replaced.” front. “This is the first step in the development of wheels.
However, the great innovation was the installation of wheels on axles. The wheels can be mounted on a shaft supported by bearings, or they can rotate freely around the shaft. This led to the development of carts, horse-drawn carriages and chariots. Samuels said archaeologists consider the appearance of a wheel spinning on an axis to be a sign of a relatively advanced civilization. The earliest evidence of a wheel on an axle was invented by the Sumerians in 3200 BC. The Chinese independently invented the wheel in 2800 BC.
In addition to reducing friction, the axle also acts as a force multiplier. If a wheel is attached to an axle and a force is used to turn the wheel, the rotational 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 shaft to achieve a similar effect.
The remaining five machines help people increase and/or change the force applied to objects. Janet L. Kolodner and her co-authors write in Moving Large Objects that “machines provide a mechanical advantage to help move objects. Mechanical advantage is a trade-off between force and distance.” For the input signal, we will ignore friction since in most cases the friction is very small compared to the input and output forces involved.
When a force is applied over a certain distance, work is done. Mathematically, this is expressed as W = F × D. For example, to lift an object, we must do work to overcome the force of gravity and move the object upward. To lift an object twice as heavy, it will take twice as much force to lift it the same distance. According to research from Auburn University, it takes twice as much effort to lift the same object twice the distance. As mathematics shows, the main advantage of machines is that they allow us to do the same amount of work using less force over a greater distance.
“Give me leverage and a fulcrum, and I can change the world.” This boastful claim is attributed to the third-century Greek philosopher, mathematician, and inventor Archimedes. While this may be a bit of an exaggeration, it does reflect the power of leverage, at least symbolically speaking, that can move the world forward.
Archimedes’ genius was that levers could be used to combine force and distance to accomplish the same amount of work. His law of leverage states that “a size is in equilibrium at a distance inversely proportional to its weight,” according to the virtual book “Archimedes in the 21st Century” by New York University’s Chris Rorres.
A lever consists of a long beam and a fulcrum or hinge. The mechanical efficiency of the 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 at 2 feet (61 cm) from the ground. We can apply 100 pounds of force. The force acting on the mass moves it upward a distance of 2 feet, and we do 200 pound-feet (271 Newton meters) of work. However, if we use a 30 ft (9 m) lever with one end under a load and a fulcrum 1 ft (30.5 cm) below the beam 10 ft (3 m) from the load, we we will only get the other end. pushed down with a weight of 50 pounds. (23 kg) strength to lift a heavy object. However, we need to lower the end of the lever 4 feet (1.2 m) to raise the load 2 feet. We compromised by doubling the distance the lever moves, but to get the same amount of work done we cut the required force in half.
A chamfer is simply a flat surface raised at an angle, such as a slope. Tilt planes are a way to lift loads that are too heavy to lift vertically, says Bob Williams, a professor in the mechanical engineering department at Ohio University’s Russ College of Engineering and Technology. The angle (steepness of the slope) determines how much effort is required to lift the load. The steeper the slope, the more effort required. This means that if we lift 100 lbs. By rolling it down a 4-foot ramp and weighing 2 feet, we halve the force required and double the distance it must travel. If we use an 8-foot ramp, we can reduce the force required to just 25 pounds. (11.3 kg).
If we want to lift the same 100 lbs. Using a rope weight, we can attach a block to a beam above the weight. This would force us to pull the rope down instead of up, but it would still require 100 pounds. force. However, if we use two pulleys – one attached to the top beam and the other to the weight – we attach one end of the rope to the beam, thread it through the pulley on the weight, and then through the pulley, we only need to pull the rope with 50 pounds of force. The strength to lift the weight even though we have to pull the rope 4 feet to lift the weight 2 feet. Again, we’re trading increased distance for decreased power.
If we want to use less force over a longer distance, we can use a pulley. According to the University of South Carolina course materials: “A pulley is a combination of blocks that reduces the force required to lift an object. The trade-off is that the pulley requires a longer rope to move something the same distance. “
Despite their simplicity, pulleys are still used in modern new cars. For example, the Hangprinter is a 3D printer that can print furniture-sized objects using a system of wires and computer-controlled pulleys attached to walls, floors and ceilings.
“A screw is essentially a long chamfer wrapped around a shaft, so its mechanical advantage can be achieved in the same way as a chamfer,” says Georgia State University. Many devices use screws that exert much more force than what is used to turn the screw. . Such devices include bench vices and lug nuts on car wheels. They derive their mechanical advantage not only from the screw itself, but in many cases also from the lever of the long handle used to turn the screw.
According to the New Mexico School of Mines and Technology, “a wedge moves an inclined plane, driven by a load to lift or a load to separate or separate.” , but wedges also serve other purposes: the main function of a wedge is to change the direction of the applied force. For example, if we wanted to split a log, we could use a sledgehammer to press a wedge into the end of the log with great force, and the wedge would redirect that force outward, causing the wood to split. Another example is a door stop, used to transmit a downward force that pushes it under the edge of the door, creating friction to prevent it from sliding along the floor.
“The Invention of the Wheel Revisited” by John H. Lienhardt, Professor Emeritus of Mechanical Engineering and History at the University of Houston. Visit the Center for Science and Industry in Columbus, Ohio for interactive explanations about simple machines. HyperPhysics (a website created by Georgia State University) also provides graphical explanations of these six simple machines.
Scott is a staff writer for How It Works magazine and has previously written for other science and news media including BBC Wildlife Magazine, Animal World Magazine, Space.com and All About History magazine. Scott holds a Master’s degree in Science and Environmental Journalism and a Bachelor’s degree in Conservation Biology from the University of Lincoln, UK. Throughout his academic and professional career, Scott has been involved in several conservation projects including the British Bird Survey, wolf monitoring in Germany and leopard tracking in South Africa.
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Post time: Dec-07-2023