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In physics
Physics

Physics is the natural science which examines basic concepts such as energy, force, and spacetime and all that derives from these, such as mass, charge, matter and its Motion ....
, a lever (from French
French language

French is a Romance language spoken around the world by around 80 million people as first language, by 190 million as second language, and by about another 200 million people as an acquired tongue, with significant speakers in 54 countries....
 lever, "to raise", c.f. a levant
Levant

The Levant describes, traditionally, the Eastern Mediterranean at large, but can be used as a geographical term that denotes a large area in Western Asia formed by the lands bordering the Eastern shores of the Mediterranean, roughly bounded on the north by the Taurus Mountains, on the south by the Arabian Desert, and on the west by the M...
) is a rigid object that is used with an appropriate fulcrum
Fulcrum

Fulcrum may refer to one of the following.*Fulcrum, the pivot on which a lever moves*Fulcrum Wheels, a bicycle wheel manufacturer, based in Italy...
 or pivot point to multiply the mechanical force that can be applied to another object. This leverage is also termed mechanical advantage
Mechanical advantage

In physics and engineering, mechanical advantage is the factor by which a mechanism multiplies the force or torque put into it. Generally, the mechanical advantage is calculated as follows:...
, and is one example of the principle of moments. A lever is one of the six simple machine
Simple machine

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 to multiply force....
s.

principle of leverage can be derived using Newton's laws of motion
Newton's laws of motion

Newton's laws of motion are three physical laws that form the basis for classical mechanics, Direct relationship the forces acting on a Physical body to the motion of the body....
, and modern statics
Statics

Statics is the branch of mechanics concerned with the analysis of loads on 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 a constant velocity....
.






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In physics
Physics

Physics is the natural science which examines basic concepts such as energy, force, and spacetime and all that derives from these, such as mass, charge, matter and its Motion ....
, a lever (from French
French language

French is a Romance language spoken around the world by around 80 million people as first language, by 190 million as second language, and by about another 200 million people as an acquired tongue, with significant speakers in 54 countries....
 lever, "to raise", c.f. a levant
Levant

The Levant describes, traditionally, the Eastern Mediterranean at large, but can be used as a geographical term that denotes a large area in Western Asia formed by the lands bordering the Eastern shores of the Mediterranean, roughly bounded on the north by the Taurus Mountains, on the south by the Arabian Desert, and on the west by the M...
) is a rigid object that is used with an appropriate fulcrum
Fulcrum

Fulcrum may refer to one of the following.*Fulcrum, the pivot on which a lever moves*Fulcrum Wheels, a bicycle wheel manufacturer, based in Italy...
 or pivot point to multiply the mechanical force that can be applied to another object. This leverage is also termed mechanical advantage
Mechanical advantage

In physics and engineering, mechanical advantage is the factor by which a mechanism multiplies the force or torque put into it. Generally, the mechanical advantage is calculated as follows:...
, and is one example of the principle of moments. A lever is one of the six simple machine
Simple machine

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 to multiply force....
s.

Theory of operation

Leverprincleple
The principle of leverage can be derived using Newton's laws of motion
Newton's laws of motion

Newton's laws of motion are three physical laws that form the basis for classical mechanics, Direct relationship the forces acting on a Physical body to the motion of the body....
, and modern statics
Statics

Statics is the branch of mechanics concerned with the analysis of loads on 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 a constant velocity....
. It is important to note that the amount of work
Mechanical work

In physics, mechanical work is the amount of energy transferred by a force acting through a distance. Like energy, it is a scalar quantity, with SI of joules....
 done is given by force
Force

In physics, a force is that which can cause an object with mass to change its velocity. Force has both Euclidean_vector#Length of a vector and Direction , making it a Vector quantity....
 times distance
Distance

Distance is a numerical description of how far apart objects are. In physics or everyday discussion, distance may refer to a physical length, a period of time, or an estimation based on other criteria ....
. 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
Fulcrum

Fulcrum may refer to one of the following.*Fulcrum, the pivot on which a lever moves*Fulcrum Wheels, a bicycle wheel manufacturer, based in Italy...
 to 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
Dimensions

Dimensions is a France project that makes educational movies about mathematics, focusing on Euclidean space. It uses POV-Ray to render some of the animations, and the films are release under a Creative Commons licence....
 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:

Load arm X load force = effort arm X effort force. If, for example, a 1 gram feather were balanced by a one kilogram rock, the feather would be 1000 times further from the fulcrum than the rock; if a 1 kilogram rock were balanced by another 1 kilogram rock, the fulcrum 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

Leverfirstclass
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.

Examples:
  1. Seesaw
    Seesaw

    A seesaw is a long, narrow board suspended in the middle so that, as one end goes up, the other goes down.In a playground setting, the board is balanced in the exact center....
     (also known as a teeter-totter)
  2. Triceps brachii muscle
    Triceps brachii muscle

    The triceps brachii is the large muscle on the back of the human upper limb. It is the muscle principally responsible for extension of the elbow joint ....
     acting on the forearm
    Forearm

    The forearm is the structure on the upper limb, between the Elbow-joint and the wrist.. This term is used in anatomy to distinguish it from the arm ....
  3. Bicycle hand brakes
    Bicycle brake systems

    Bicycle brake systems are used to slow down,or brake a bicycle. There have been various types through history, and several are still in use today....
  4. Trebuchet
    Trebuchet

    A trebuchet or trebucket is a siege engine that was employed in the Middle Ages either to smash masonry walls or to throw projectiles over them....
  5. Crowbar
    Crowbar (tool)

    A crowbar, pry bar, or prybar, more informally a jimmy, jimmy bar, jemmy or gooseneck is a tool consisting of a metal pole with a single curved end and flattened points, often with a small fissure on one or both ends for removing nail ....
     (curved end of it)
  6. Hammer Claw
    Claw hammer

    A claw hammer is a tool primarily used for pounding nail into, or extricating nails from, some other object. Generally, a claw hammer is associated with woodworking but is not limited to use with wood products....
    , when pulling a nail with the hammer's claw
  7. Hand truck
    Hand truck

    A hand truck is an L-shaped box-moving cart with handles at one end, wheels at the base, with a small ledge to set objects on, flat against the floor when the hand-truck is upright....
    s are L-shaped but work on the same principle, with the axis as a fulcrum
  8. Pliers
    Pliers

    Sorry, no overview for this topic
     (double lever)
  9. Scissors
    Scissors

    Scissors are hand operated cutting instruments, and for people without hands, there is also the option of using a specially designed foot operated style....
     (double lever)
  10. Shoehorn
  11. Spud bar
    Spud bar

    A spud bar is a long straight metal bar used lengthwise as a hand tool to deliver blows to a target, causing the target to move, break up or deform....
     (moving heavy objects)
  12. Beam engine
    Beam engine

    A beam engine is a design of engine based on the principles of a first-class lever. A force is applied to one end of a beam, which is pivoted in the middle, and the lever action transfers the force to create work at the other end of the beam....
     although here the aim is just to change the direction in which the applied force acts, since the fulcrum is normally in the center of the beam (i.e. D1 = D2)
  13. Wheel and axle
    Wheel and axle

    The wheel and axle is a simple machine.The traditional form as recognized in 19th century textbooks is as shown in the image. This also shows the most widely recognized application, i.e., lifting water from a well....
     because the wheel's motions follows the fulcrum, load arm, and effort arm principle.


Second-class levers

Leversecondclass
In a second class lever the input effort is located at the 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:
  1. Dental elevator
  2. Nutcracker
    Nutcracker

    A nutcracker is a mechanical device for cracking nut . Usually they work on the principle of moment s as described in Archimedes' analysis of the lever....
  3. Paddle
    Paddle

    A paddle is a tool used for pushing against liquids, either as a form of Marine propulsion in a boat or as an implement for mixing....
  4. Curb bit
    Curb bit

    A curb bit is a type of bit used for equestrianism horses that uses lever action. It includes the pelham bit and the double bridle along with the traditional "curb bit" used mainly by western riding....
  5. Wheelbarrow
    Wheelbarrow

    A wheelbarrow is a small hand-propelled vehicle, usually with just one wheel, designed to be pushed and guided by a single person using two handles to the rear or a sail may be used to guide the ancient wheelbarrow by wind....
  6. Wrench
    Wrench

    A wrench or spanner is a tool used to provide a mechanical advantage in applying torque to turn screw, Nut or other items designed to interface with a wrench....
  7. Bottle opener
    Bottle opener

    A bottle opener is a device that enables the removal of metal bottle caps from bottles. More generally, it might be thought to include Corkscrew s used to remove cork or plastic stoppers from wine bottles....
  8. Diving Board
    Diving board

    Diving board may refer to:*Springboard*Diving platform, referred to as a "tower" or sometimes "firm board"...
     (spring board)
  9. Crowbar
    Crowbar (tool)

    A crowbar, pry bar, or prybar, more informally a jimmy, jimmy bar, jemmy or gooseneck is a tool consisting of a metal pole with a single curved end and flattened points, often with a small fissure on one or both ends for removing nail ....
     (flat end)
  10. Push-up
  11. Doorknob(could be a wheel and axle also)
  12. Oars (the object is to move the boat, NOT the water).


Third-class levers

Thirdclasslever
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. Examples
  1. Baseball bat
    Baseball bat

    A baseball bat is a smooth wooden or metal Club used in the game of baseball to hit the Baseball after the ball is thrown by the pitcher . It is no more than 2.75 inches in diameter at the thickest part and no more than 42 inches in length....
  2. Biceps brachii muscle
    Biceps brachii muscle

    In human anatomy, the biceps brachii is a muscle located on the upper arm. The biceps has several functions, the most important being to rotate the forearm and to flex the elbow....
     acting on the forearm
    Forearm

    The forearm is the structure on the upper limb, between the Elbow-joint and the wrist.. This term is used in anatomy to distinguish it from the arm ....
     
  3. Boat paddle
  4. Broom
    Broom

    A broom is a cleaning tool consisting of stiff fibres attached to, and roughly parallel to, a cylinder handle , the broomstick. In the context of witchcraft, "broomstick" is likely to refer to the broom as a whole....
  5. Electric Gates
    Electric gates

    Electric gates are an easy way to ensure the security of private premises and can be used for all sized properties. Electric gates, though not very commonplace at the moment, have found their niche in the market today....
  6. Fishing rod
    Fishing rod

    A fishing rod or a fishing pole is a tool used to Fishing, usually in conjunction with the sport of angling, can also be used in competition casting ....
  7. Hockey stick
    Hockey stick

    A hockey stick is a piece of equipment used in field hockey, ice hockey, or roller hockey to move the ball or puck....
  8. Mandible
    Mandible

    The mandible or inferior maxillary bone forms the lower jaw and holds the lower tooth in place. It also refers to both the upper and lower sections of the beaks of birds....
  9. Mousetrap (Spring-loaded bar type)
    Mousetrap

    See also Mouse Trap A mousetrap is a specialized type of animal trap designed primarily to catch mouse; however, it may also trap other small animals....
  10. Nail clippers, the main body handle exerts the incoming force
  11. Shovel
    Shovel

    A shovel is a tool for lifting and moving loose material such as coal, gravel, snow, soil, or sand and is an extremely common tool which is used extensively in agriculture, construction and gardening....
     (the action of picking or lifting up sand or dirt)
  12. Stapler
    Stapler

    A stapler is a mechanical device that joins together sheets of paper or other similar materials by driving a thin metal staple through the sheets and folding over the ends to secure the paper....
  13. Tongs
    Tongs

    Tongs are wikt:gripping and lifting tools, of which there are many forms adapted to their specific use. Some are merely large pincers or nipper s, but the greatest number fall into three classes:...
  14. Tweezers
    Tweezers

    Tweezers are tools used for picking up small objects that are not easily handled with the human hands. They are probably derived from tongs, Pincer s, or scissors-like pliers used to grab or hold hot objects from the dawn of recorded history....
  15. Hammer
    Hammer

    A hammer is a tool meant to deliver an impact to an object. The most common uses are for driving Nail s, fitting parts, and breaking up objects....


See also

  • Engineering mechanics
  • Engineering vehicles
  • Linkage (mechanical)
    Linkage (mechanical)

    A mechanical linkage is a series of rigid links connected with joints to form a closed chain, or a series of closed chains. This is created by two or more levers that are put together....
  • Switch
    Switch

    In electronics, a switch is an electrical component which can break an electrical circuit, interrupting the Electric current or diverting it from one conductor to another....
  • Archimedes
    Archimedes

    Archimedes of Syracuse was a Greek mathematics, physicist, engineer, inventor, and astronomer. Although few details of his life are known, he is regarded as one of the leading scientists in classical antiquity....


External links

  • at Diracdelta science and engineering encyclopedia
  • by Stephen Wolfram
    Stephen Wolfram

    Stephen Wolfram is a British physicist, mathematician and businessman known for his work in theoretical particle physics, cosmology, cellular automaton, complexity theory, and computer algebra....
    , Wolfram Demonstrations Project
    Wolfram Demonstrations Project

    The Wolfram Demonstrations Project is a website developed by Wolfram Research, whose stated goal is to bring computational exploration to the widest possible audience....
    .
  • at EnchantedLearning.com