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 that can be applied to another object. This is also termed mechanical advantage, and is one example of the principle of moments. A lever is one of the six simple machines. Look up Leverage in Wiktionary, the free dictionary Leverage may refer to one of the following. ... Image File history File links Size of this preview: 800 × 359 pixelsFull resolution (888 × 398 pixel, file size: 33 KB, MIME type: image/jpeg) (All user names refer to es. ... Image File history File links Size of this preview: 800 × 359 pixelsFull resolution (888 × 398 pixel, file size: 33 KB, MIME type: image/jpeg) (All user names refer to es. ... A magnet levitating above a high-temperature superconductor demonstrates the Meissner effect. ... The Levant The Levant (IPA: ) is an imprecise geographical term historically referring to a large area in the Middle East south of the Taurus Mountains, bounded by the Mediterranean Sea on the west, and by the northern Arabian Desert and Upper Mesopotamia to the east. ... Look up Fulcrum in Wiktionary, the free dictionary. ... In physics and engineering, mechanical advantage (MA) is the factor by which a mechanism multiplies the force put into it. ... See also moment (mathematics) for a more abstract concept of moments that evolved from this concept of physics. ... This article is about the concept in physics. ...

Theory of operation

The principle of the lever tells us that the above is in static equilibrium, with all forces balancing, if F₁D₁ = F₂D₂.

The principle of leverage can be derived using 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. For instance, to use a lever to lift a certain unit of weight with a force of half a unit, the distance from the fulcrum of the spot where force is applied must be twice 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. Image File history File links LeverPrincleple. ... Image File history File links LeverPrincleple. ... In physics, static equilibrium, or neutral balance, exists when the forces (actions), and torques, on all components of a defined system are balanced such that no component is undergoing an acceleration relative to the designated frame of reference. ... Newtons First and Second laws, in Latin, from the original 1687 edition of the Principia Mathematica. ... Statics is the branch of physics concerned with physical systems in static equilibrium, that is, in a state where the relative positions of subsystems do not vary over time, or where components and structures are at rest under the action of external forces of equilibrium. ... In physics, mechanical work is the amount of energy transferred by a force. ... For other uses, see Force (disambiguation). ... Distance is a numerical description of how far apart objects are at any given moment in time. ... Look up Fulcrum in Wiktionary, the free dictionary. ... Dimension (from Latin measured out) is, in essence, the number of degrees of freedom available for movement in a space. ...

Archimedes was the first to explain the principle of the lever, stating: For other uses, see Archimedes (disambiguation). ...

"(equal) weights at equal distances are in equilibrium, and equal weights at unequal distances are not in equilibrium but incline towards the weight which is at the greater distance."

Archimedes once famously remarked: "Πα βω και χαριστιωνι ταν γαν κινησω πασαν." ("Give me a place to stand and with a lever I will move the whole world.")

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:

Load arm X load force = effort arm X effort force. When 2 things are balanced, when a 1 gram feather for instance is balanced by a one kilogram rock on a lever the feather would go up and the rock would go down, but if a 1 kilogram rock was balanced by a 1 kilogram rock, the lever would be in the middle.

The three classes of levers

There are three classes of levers which represent variations in the location of the fulcrum and the input and output forces.

First-class levers

First class lever

A first-class lever is a lever in which the fulcrum is located between the input effort and the output load. In operation, a force is applied (by pulling or pushing) to a section of the bar, which causes the lever to swing about the fulcrum, overcoming the resistance force on the opposite side. The fulcrum may be at the center point of the lever as in a seesaw or at any point between the input and output. This supports the effort arm and the load. Image File history File links LeverFirstClass. ... Image File history File links LeverFirstClass. ...

Examples:

1. Beam engine although here the aim is just to change the direction in which the applied force acts, since the fulcrum is normally in the centre of the beam (i.e. D1 = D2)
2. Bicycle hand brakes
3. Can opener and bottle opener
4. Crowbar
5. Curb bit
6. Hammer, when pulling a nail with the hammer's claw
7. Hand trucks are L-shaped but work on the same principle, with the axis as a fulcrum
8. Oars
9. Pliers (double lever)
10. Scissors (double lever)
11. Seesaw (also known as a teeter-totter)
12. Shoehorn
13. Spud bar (moving heavy objects)
14. Trebuchet, an upside down example of the above picture
15. Wheel and axle because the wheel's motions follows the fulcrum, load arm, and effort arm principle

The remains of a beam engine at Wanlockhead A beam engine is a design of stationary steam engine. ... Linear-pull brake on rear wheel of a mountain bike Bicycle brake systems are used to slow down, or brake a bicycle. ... Church key refers to various kinds of bottle and can openers. ... A bottle opener is primarily thought of as a device which enables the removal of metal bottle caps from bottles, though more generally it might be thought to include corkscrews used to remove cork or plastic stoppers from wine bottles. ... A crowbar A crowbar, also called a pry bar or prybar, or more informally known as a jimmy, jimmy bar or jemmy (British Isles), is a tool consisting of a metal bar with a single curved end and flattened points, often with a small fissure on the curved end for... A curb bit is a type of bit used for riding that uses leverage. ... For other uses, see Hammer (disambiguation). ... An unloaded hand-truck. ... An oar is an implement used for water-borne propulsion. ... For the Jamaican singer, see Pliers (singer). ... For other uses, see Scissors (disambiguation). ... Modern seesaws have springs for safer play. ... This article is being considered for deletion in accordance with Wikipedias deletion policy. ... A spud bar, scale in inches/feet A spud bar is a hand tool designed to deliver blows to a target, causing the target to move or deform. ... For the typeface, see Trebuchet MS. Trebuchet at Château des Baux, France A trebuchet is a siege engine employed in the Middle Ages either to smash masonry walls or to throw projectiles over them. ... A pair of metal wheels with bearings fitted to cranked axle. ...

Second-class levers

Second class lever

In a second class lever the input effort is located at one end of the bar and the fulcrum is located at the other end of the bar, opposite to the input, with the output load at a point between these two forces. Examples: Image File history File links LeverSecondClass. ... Image File history File links LeverSecondClass. ...

1. Dental elevator
2. Door
3. Nutcracker
4. Paddle
5. Springboard (diving board)
6. Wheelbarrow
7. Wrench

Mouth mirror, a commonly used dental istrument Dental instruments refer to the tools which dental professionals use to provide dental treatment. ... This article is about the architectural feature. ... This article is about the tool for cracking nuts. ... A paddle is a tool, originally a propulsion implement for mixing or pushing against liquids, typically in order to propel a boat. ... Diving off a springboard A springboard or diving board is used for diving and is a board that is itself a spring, i. ... A common wheelbarrow Older wheelbarrow Wheelbarrows on the Belomorkanal A wheelbarrow is a small one-wheeled, hand-propelled vehicle, designed to be pushed and guided by a single person using two handles to the rear. ... Combination wrench, or combination spanner (left: box-end/ring, right: open-end) A wrench or spanner is a tool used to provide a mechanical advantage in applying torque to turn bolts, nuts or other hard-to-turn items. ...

Third-class levers

Third class lever. For the lever in this diagram to work correctly, one must assume that the fulcrum is attached to the bar.

For this class of levers, the input effort is higher than the output load, which is different from second-class levers and some first-class levers. However, the distance moved by the resistance (load) is greater than the distance moved by the effort. Since this motion occurs in the same length of time, the resistance necessarily moves faster than the effort. Thus, a third-class lever still has its uses in making certain tasks easier to do. In third class levers, effort is applied between the output load on one end and the fulcrum on the opposite end. Image File history File links ThirdClassLever. ... Image File history File links ThirdClassLever. ...

Examples:

1. Arm
2. Baseball bat
3. Boat paddle
4. Broom
5. Door
6. Fishing rod
7. Hockey stick
8. Tongs
9. Tweezers
10. Mandible
11. Mousetrap
12. Nail clippers, the main body handle exerts the incoming force
13. Shovel (the action of picking or lifting up sand or dirt)
14. Sling
15. Tools, such as a hoe or scythe
16. Stapler

Look up ARM in Wiktionary, the free dictionary. ... Four historically significant baseball bats showcased in the National Baseball Hall of Fames traveling exhibit Baseball As America. ... For other uses, see Paddle (disambiguation). ... broom A broom is a cleaning tool consisting of stiff fibres attached to, and roughly parallel to, a cylindrical handle, the broomstick. ... This article is about the architectural feature. ... A fiberglass spinning rod and reel circa 1997. ... Field hockey stick Girl with a field hockey stick In climatology, the Hockey Stick graph is a nickname for a rising temperature reconstruction. ... Tongs used for cooking or serving food Tongs are gripping and lifting tools, of which there are many forms adapted to their specific use. ... Tweezers are tools used for picking up small objects that are not easily handled with the human hands. ... The mandible (from Latin mandibŭla, jawbone) or inferior maxillary bone is, together with the maxilla, the largest and strongest bone of the face. ... For other uses, see Mousetrap (disambiguation). ... Categories: Stub ... Shovel with wide blade - especially appropriate for lifting snow or coal A shovel is a tool for lifting and moving loose material such as coal, gravel, snow, soil, or sand. ... Home-made sling. ... Agricultural square bladed hoe. ... A traditional wooden scythe A scythe (IPA: , most likely from Old English siðe, sigði) is an agricultural hand tool for mowing and reaping grass or crops. ... A standard office stapler A Stapler combines together sheets of paper or other materials by driving a thin metal staple through the sheets and folding over the ends to secure the paper. ...

Mnemonic

A mnemonic for remembering the three classes of levers is the word flex, where the letters f-l-e represent the fulcrum, the load, and the effort as being between the other two, in the first-class lever, the second-class lever, and the third-class lever respectively. (To relate the mnemonic to the above diagrams, note that: the "fulcrum" is represented by the triangle, the "effort" is denoted by the arrow with a hand symbol, and the "load" is the other arrow.) To remember what the different classes of levers look like, another mnemonic is "fre 123" In a 1st class lever the fulcrum is in the middle, 2nd class the resistance is in the middle, and 3rd class the effort is in the middle of it. Alternatively, the term 'Frogs lay eggs' can also be used in the similar manner. Some people remember the word 'elf', which sorts the classes from the third to first. Another way is "FREE Lever" Which means Fulcrum + Resistance + Effort Equals Lever. For other uses, see Mnemonic (disambiguation). ...

See also

• Engineering mechanics
• Engineering vehicles
• Linkage (mechanical)
• Simple machine
• Switch
• Archimedes

Engineering mechanics is a branch of the physical sciences which looks to understand the actions and reactions of bodies at rest or in motion. ... An excavator Engineering vehicles are heavy-duty vehicles, specially designed for executing engineering tasks. ... The locking pliers is an example of a four-bar, one degree of freedom mechanical linkage; or a five-bar, two DOF linkage when the adjustment screw is considered. ... This article is about the concept in physics. ... Electrical switches. ... For other uses, see Archimedes (disambiguation). ...

External links

Wikimedia Commons has media related to:

Levers

Look up Lever in
Wiktionary, the free dictionary.

• Lever at Diracdelta science and engineering encyclopedia
• A Simple Lever by Stephen Wolfram, The Wolfram Demonstrations Project.
• Levers: Simple Machines at EnchantedLearning.com