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[[File:lighterstill.jpg]][[File:Lever.jpg|right|frame]]

[[File:lighterstill.jpg]][[File:Lever.jpg|right|frame]]

In [[physics]], a '''lever''' (from French lever, "to raise", c.f. a levant) is a rigid object that is used with an appropriate [[fulcrum]] or pivot point to multiply the [[mechanical]] [[force]] that can be applied to another object. This leverage is also termed mechanical advantage, and is one example of the principle of moments. A lever is one of the six [http://en.wikipedia.org/wiki/Simple_machine simple machine]s. [http://en.wikipedia.org/wiki/Archimedes Archimedes] once said, "Give me a lever long enough and a fulcrum on which to place it, and I shall move the world." First class levers are similar but not the same as second or third class levers, in which the fulcrum, resistance, and effort are in different locations.

In [[physics]], a '''lever''' (from French lever, "to raise", c.f. a levant) is a rigid object that is used with an appropriate [[fulcrum]] or pivot point to multiply the [[mechanical]] [[force]] that can be applied to another object. This leverage is also termed mechanical advantage, and is one example of the principle of moments. A lever is one of the six [https://en.wikipedia.org/wiki/Simple_machine simple machine]s. [https://en.wikipedia.org/wiki/Archimedes Archimedes] once said, "Give me a lever long enough and a fulcrum on which to place it, and I shall move the world." First class levers are similar but not the same as second or third class levers, in which the fulcrum, resistance, and effort are in different locations.

==Theory of operation==

==Theory of operation==

The principle of leverage can be derived using [http://en.wikipedia.org/wiki/Newton%27s_laws_of_motion Newton's laws of motion], and modern statics. It is important to note that the amount of work done is given by force times distance. To use a lever to lift a certain unit of weight with a force of half a unit, the distance from the [[fulcrum]] to the spot where force is applied must be exactly twice that of the distance between the weight and the fulcrum. For example, to cut in half the force required to lift a weight resting 1 meter from the fulcrum, we would need to apply force 2 meters from the other side of the [[fulcrum]]. The amount of work done is always the same and independent of the dimensions of the lever (in an ideal lever). The lever only allows to trade force for distance.

The principle of leverage can be derived using [https://en.wikipedia.org/wiki/Newton%27s_laws_of_motion Newton's laws of motion], and modern statics. It is important to note that the amount of work done is given by force times distance. To use a lever to lift a certain unit of weight with a force of half a unit, the distance from the [[fulcrum]] to the spot where force is applied must be exactly twice that of the distance between the weight and the fulcrum. For example, to cut in half the force required to lift a weight resting 1 meter from the fulcrum, we would need to apply force 2 meters from the other side of the [[fulcrum]]. The amount of work done is always the same and independent of the dimensions of the lever (in an ideal lever). The lever only allows to trade force for distance.

The point where you apply the force is called the effort. The effect of applying this force is called the load. The load arm and the effort arm are the names given to the distances from the fulcrum to the load and effort, respectively. Using these definitions, the Law of the Lever is:

The point where you apply the force is called the effort. The effect of applying this force is called the load. The load arm and the effort arm are the names given to the distances from the fulcrum to the load and effort, respectively. Using these definitions, the Law of the Lever is:

:7. Hammer

:7. Hammer

==External links==

==External links==

* [http://www.diracdelta.co.uk/science/source/l/e/lever/source.html Lever at Diracdelta science and engineering encyclopedia]

* [https://www.diracdelta.co.uk/science/source/l/e/lever/source.html Lever at Diracdelta science and engineering encyclopedia]

* [http://demonstrations.wolfram.com/ASimpleLever/ A Simple Lever] by Stephen Wolfram, Wolfram Demonstrations Project.

* [https://demonstrations.wolfram.com/ASimpleLever/ A Simple Lever] by Stephen Wolfram, Wolfram Demonstrations Project.

* [http://www.enchantedlearning.com/physics/machines/Levers.shtml Levers: Simple Machines] at EnchantedLearning.com

* [https://www.enchantedlearning.com/physics/machines/Levers.shtml Levers: Simple Machines] at EnchantedLearning.com

[[Category: Physics]]

[[Category: Physics]]