Most people think about mechanical components when they think of the word "machine." In fact, images of airplanes, cars, computers, cell phones, and power saws come to mind when asked to think about machines. What they may not realize is that not every machine requires a motor to run. What about manually powered machines, such as a bicycle, tennis racquet, scissors, nail clippers, and bottle openers? These objects do not possess mechanical components, yet they perform a specific task. These simple machines have earned their name because they do not require anything complex for them to work. Simple machines can help increase force, inertia, elevation, and change the direction of heavier things. They can fasten, pull, split, cut, and quicken heavy objects. If an object causes a person to exert force to cause a motion, then it requires work from both the machine and the individual. The following article addresses information about simple machines, such as wheels and axles, levers, pulleys, screws, inclined planes, and compound machines in the context of automobiles.
Wheels and Axles
A wheel increases force and distance when mounted on an object. Gears or axles transfer the force to cause the target object to move a desired distance. In other words, applied force causes motion in an object allowing it to travel a certain distance. Common examples include door knobs, bicycle pedals, car wheels, airplane propellers, and water faucets. When somebody turns a door knob, they are applying force by turning a larger knob that also turns a smaller knob. In addition, when a bicyclist turns a bicycle axle, it yields a great distance as the bicycle's wheel turns.
Inclined planes, also known as sloping surfaces, stay still. This allows for less force traveled over greater distances. Common examples include stairs, escalators, and ramps. Inclined planes allow heavier objects to travel off the ground without exerting a lot of effort. The Ancient Egyptians used rollers and inclined planes to construct the pyramids. It helped assist in the replacement of limestone blocks that weighed about 70,000 tons each.
A lever exchanges less force over greater distances or more force over shorter distances. Common examples include crowbars, seesaws, bottle openers, and claw hammers. Levers typically have three parts, including the resistance from the target objected intended to be lifted, the applied force when using the lever, and the fulcrum. The fulcrum is the fixed point on a lever that pivots. Levers vary depending on the location of the fulcrum. Seesaws have a fulcrum wedged between the applied force and the target object. A bottle opener places the fulcrum on one side while the individual applies force at the opposite end. The object intended to move resides in the middle.
A pulley, a wheel with a grooved rim, holds a rope that changes the direction of an object. A fixed pulley does not change the force, speed, or distance of an object. Common examples include curtains, mini-blinds, and pole flags. Pulleys allow individuals to pull an object upwards using a rope and body weight. A pulley turns around axles.
Contrary to popular opinion, screws are more than objects used to fasten things together. Screws are inclined planes that wrap around cylinders. Screw threads have tiny ramps that encircle the actual screw. Screws require less force and allow for changes to be made in the direction an object is going. Common examples include meat grinders, helicopter blades, boat propellers, lids, jars, and bar stools. Bolts and nuts are the most common form of screws. The majority of machines have at least one screw in them.
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Compound machines consist of multiple simple machines. Most mechanical machines are categorized as compound machines. Compound machines perform complex functions that simple machines may not be able to perform on their own. This gives them a mechanical edge over their counterparts. Common examples include scissors and bicycles.