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This article is about the simple machine. For other uses, see Lever (disambiguation).
Levers can be used to exert a large force over a small distance at one end by exerting only a small force over a greater distance at the other.
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 (effort) that can be applied to another object (load).^ The force applied to the implement control lever is in proportion to the load being applied to...
  • Force feedback lever - Google Patent Search 2 February 2010 15:19 UTC www.google.com [Source type: Reference]

 ^ Providing interactions between simulated objects using force feedback .
  • Force feedback lever - Google Patent Search 2 February 2010 15:19 UTC www.google.com [Source type: Reference]

 ^ Graphical click surfaces for force feedback applications to provide user selection using cursor interaction with a trigger position within a boundary of a graphical object .
  • Force feedback lever - Google Patent Search 2 February 2010 15:19 UTC www.google.com [Source type: Reference]

 This leverage is also termed mechanical advantage, and is one example of the principle of moments. A lever is one of the six simple machines.

Contents

Early

The earliest remaining writings regarding levers date from the 3rd century BC and were provided by Archimedes. ."Give me a place to stand, and I shall move the earth." is a remark of Archimedes who formally stated the correct mathematical principle of levers (quoted by Pappus of Alexandria).^ The ancient Greek philosopher Archimedes is quoted as having said : Give me a place to stand and with a lever I will move the whole world.

 ^ Name: Lever's Blues Location: Michigan, United States I decided to try to give back to those who have given me so much enjoyment over the years.

 ^ It was because we were having so many problems with paper ballots that we moved to the lever in the first place.
  • A Love Affair With Lever Voting Machines - City Room Blog - NYTimes.com 2 February 2010 15:19 UTC cityroom.blogs.nytimes.com [Source type: News]
In ancient Egypt, constructors used the lever to move and uplift obelisks weighting more than 100 tons.

Force and levers

.The force applied (at end points of the lever) is proportional to the ratio of the length of the lever arm measured between the fulcrum (pivoting point) and application point of the force applied at each end of the lever.^ The force applied to the implement control lever is in proportion to the load being applied to...
  • Force feedback lever - Google Patent Search 2 February 2010 15:19 UTC www.google.com [Source type: Reference]

 ^ The hole punch according to claim 1, wherein the base comprises a first upstanding portion at the first end of the base and a second upstanding portion at the second end of the base, the first end of the first lever arm pivotally connected to the first upstanding portion, the first end of the second lever arm pivotally connected to the second upstanding portion.
  • Hole punch - Patent application - includes a base and a lever system to actuate a punch 2 February 2010 15:19 UTC www.faqs.org [Source type: Reference]

 ^ The lever system 20 includes a first lever arm 22 pivotally joined to the upstanding end portion 14, and a second pivotal arm 24 pivotally joined to the opposite upstanding portion 16 of the base.
  • Hole punch - Patent application - includes a base and a lever system to actuate a punch 2 February 2010 15:19 UTC www.faqs.org [Source type: Reference]

 Mathematically, this is expressed by M = Fd.

Classes

There are three classes of levers representing variations in the relative locations of the fulcrum, the load and the force:[1]
.
  • Class 1: the fulcrum is located between the applied force and the load.^ The force applied to the implement control lever is in proportion to the load being applied to...
    • Force feedback lever - Google Patent Search 2 February 2010 15:19 UTC www.google.com [Source type: Reference]

     ^ An actuator means applies a force to the control lever in response to a sensed load being applied to the work implement.
    • Force feedback lever - Google Patent Search 2 February 2010 15:19 UTC www.google.com [Source type: Reference]

     Example: the crowbar.
  • Class 2: the load is situated between the fulcrum and the force. .Example: the wheelbarrow.
  • Class 3: the force is applied between the fulcrum and the load.^ The force applied to the implement control lever is in proportion to the load being applied to...
    • Force feedback lever - Google Patent Search 2 February 2010 15:19 UTC www.google.com [Source type: Reference]

     ^ An actuator means applies a force to the control lever in response to a sensed load being applied to the work implement.
    • Force feedback lever - Google Patent Search 2 February 2010 15:19 UTC www.google.com [Source type: Reference]

     Example: the human elbow joint on flexion.

In the real world

For the classical mechanics formulas to work, or to be a good approximation of real world applications, the lever must be made from a combination of rigid bodies, i.e. a beam and a rigid fulcrum. Any bending or other deformation must be negligible.

See also

References

  1. ^ Davidovits, Paul (2008), Physics in Biology and Medicine, Third edition, Academic Press, p. 10, ISBN 978-0-12-369411-9, http://books.google.be/books?id=e9hbt3xisb0C , Chapter 1, p. 10

External links

Simple machine
Classical simple machines
Inclined plane · Lever · Pulley · Screw · Wedge · Wheel and axle

1911 encyclopedia

Up to date as of January 14, 2010
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From LoveToKnow 1911

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Gaming

Up to date as of January 31, 2010

From Wikia Gaming, your source for walkthroughs, games, guides, and more!

Can control traps, doors and Floodgates. Build them in a Mechanic's workshop

This article uses material from the "Lever" article on the Gaming wiki at Wikia and is licensed under the Creative Commons Attribution-Share Alike License.

Simple English

[[File:|thumb|240px|Diagram of the use of a first-class lever (blue) on a fulcrum (brown)]] A lever is scientific term for something generally used in physics. A lever is something that can be used in a lot of ways. One way is by measuring things, or by seeing which weighs more. A lever is supported by a fulcrum which it uses to lifts weights. It is one of six simple machines. The famous scientist Archimedes once said, "Give me a lever long enough and a fulcrum on which to place it, and I shall move the world". There are three types of levers: First-class, Second-class and Third-class.

Contents

Early

The earliest remaining writings regarding levers date from the 3rd century BC and were provided by Archimedes. "Give me a place to stand, and I shall move the earth." is a famous quote of Archimedes who stated the correct mathematical principle of levers (quoted by Pappus of Alexandria).[1]

The Three Kinds of Levers

There are three kinds of levers. The difference between them is where the fulcrum is and where the forces are.

First Class

A first-class lever is a lever where the fulcrum is in between the effort and resistance (the load).

Second Class

A second-class lever is where the resistance (the load) is between the effort and the fulcrum.

Third Class

A third-class lever is where the effort is in between the resistance (the load) and the fulcrum.

References

  1. ↑ Mackay, Alan Lindsay (1991). "Archimedes ca 287–212 BC". A Dictionary of scientific quotations. London: Taylor and Francis. p. 11. ISBN 9780750301060. 
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Up to date as of December 23, 2010

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