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A simple machine is a mechanical device that changes the direction or magnitude of a force. [1] In general, they can be defined as the simplest mechanisms that use mechanical advantage (also called leverage) to multiply force. [2] Usually the term refers to the six classical simple machines that were defined by Renaissance scientists: [3] [4 ...
Examples of rope and pulley systems illustrating mechanical advantage. Consider lifting a weight with rope and pulleys. A rope looped through a pulley attached to a fixed spot, e.g. a barn roof rafter, and attached to the weight is called a single pulley. It has a mechanical advantage (MA) = 1 (assuming frictionless bearings in the pulley ...
The earliest evidence of pulleys dates back to Ancient Egypt in the Twelfth Dynasty (1991–1802 BC) [1] and Mesopotamia in the early 2nd millennium BC. [2] In Roman Egypt, Hero of Alexandria (c. 10–70 AD) identified the pulley as one of six simple machines used to lift weights. [3]
The rope is threaded through the pulleys to provide mechanical advantage that amplifies that force applied to the rope. [4] In order to determine the mechanical advantage of a block and tackle system consider the simple case of a gun tackle, which has a single mounted, or fixed, pulley and a single movable pulley.
Atwood's machine is a common classroom demonstration used to illustrate principles of classical mechanics. The ideal Atwood machine consists of two objects of mass m 1 and m 2, connected by an inextensible massless string over an ideal massless pulley. [1] Both masses experience uniform acceleration.
The mechanical belt drive, using a pulley machine, was first mentioned in the text of the Dictionary of Local Expressions by the Han Dynasty philosopher, poet, and politician Yang Xiong (53–18 BC) in 15 BC, used for a quilling machine that wound silk fibres onto bobbins for weavers' shuttles. [1]
The earliest evidence of pulleys date back to Mesopotamia in the early 2nd millennium BC, [7] and ancient Egypt during the Twelfth Dynasty (1991-1802 BC). [8] The screw, the last of the simple machines to be invented, [9] first appeared in Mesopotamia during the Neo-Assyrian period (911-609) BC. [10]
A dumb pulley can lift very large masses a short distance. It consists of two fixed pulleys of unequal radii that are attached to each other and rotate together, a single pulley bearing the load, and an endless rope looped around the pulleys. To avoid slippage, the rope is usually replaced by a chain, and the connected pulleys by sprockets.