Simple machine Totally Explained

Everything about Simple Machine totally explained

In physics and mechanics a simple machine is a mechanical device that changes the direction or magnitude of a force. In general, they can be defined as the simplest mechanisms that use mechanical advantage (also called leverage) to multiply force. A simple machine uses a single applied force to do work against a single load force. Ignoring friction losses, the work done on the load is equal to the work done by the applied force. They can be used to increase the amount of the output force, at the cost of a proportional decrease in the distance moved by the load. The ratio of the output to the input force is called the mechanical advantage.
Usually the term refers to the six classical simple machines which were defined by Renaissance scientists:.

Lever
Wheel and axle
Pulley
Inclined plane
Wedge
Screw They are the elementary 'building blocks' of which all complicated machines are composed. For example, wheels, levers, and pulleys are all used in the mechanism of a bicycle. In the 20th century, a realization that at least one simple machine, the hydraulic press, had been left out, and arguments that some of the six classical devices can be considered as modifications of others (see below), has led some modern sources to avoid specifying any list of simple machines as 'basic'. Nevertheless, the above six are what is usually meant by 'simple machine' and are still regarded as the foundation of mechanical technology.

Simple machines fall into two classes; those dependent on the vector resolution of forces (inclined plane, wedge, screw) and those in which there's an equilibrium of torques (lever, pulley, wheel).

History

The idea of a 'simple machine' originated with the Greek philosopher Archimedes around the 3nd century BC, who studied the 'Archimedean' simple machines: lever, pulley, and screw. He discovered the principle of leverage, or mechanical advantage. His understanding was limited to the static balance of forces and didn't include the tradeoff between force and distance moved. Heron of Alexandria (ca. 10-75 CE) in his work 'Mechanics' lists 5 mechanisms with which a load can be set in motion: winch, lever, pulley, wedge, and screw. During the Renaissance the classic 5 simple machines (excluding the wedge) began to be studied as a group. The complete dynamic theory of simple machines was worked out by Galileo Galilei in 1600 in Le Meccaniche ('On Mechanics'). He was the first to understand that simple machines don't create energy, only transform it.

Alternate definitions

Some variations that have been proposed to the classical list of six simple machines:

Some say there are only five simple machines, arguing that the wedge is a moving inclined plane.

Others further simplify the list to four saying that the screw is a helical inclined plane. This position is less accepted because a screw simultaneously converts a rotational force (torque) to a linear force.

Some go even further to insist that only two simple machines exist, as a pulley and wheel and axle can be viewed as unique forms of levers, leaving only the lever and the inclined plane.

Hydraulic systems can also provide amplification of force, so some say they should be added to the list.

Frictionless analysis

Although each machine works differently, the way they function is similar mathematically. In each machine, a force

F_  ,

In the screw, which uses rotational motion, the input force should be replaced by the torque, and the distance by the angle the shaft is turned.

Footnotes

Further Information

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