In physics, a lever (from French lever, "to raise", c. Physics (Greek Physis - φύσις in everyday terms is the Science of Matter and its motion. French ( français,) is a Romance language spoken around the world by 118 million people as a native language and by about 180 to 260 million people 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. See also Names of the Levant The Levant (lə'vænt is a geographical term that denotes a large area in Western Asia, roughly bounded on the north by the This is also termed mechanical advantage, and is one example of the principle of moments. In Physics and Engineering, mechanical advantage (MA is the factor by which a mechanism multiplies the force put into it In Physics, the moment of force (often just moment, though there are other quantities of that name such as Moment of inertia) is a Pseudovector A lever is one of the six simple machines. In Physics, especially Mechanics, a simple machine is a mechanical device that changes the direction or magnitude of a Force.
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Theory of operation
The principle of leverage can be derived using Newton's laws of motion, and modern statics. Newton's laws of motion are three Physical laws which provide relationships between the Forces acting on a body and the motion of the Statics is the branch of Mechanics concerned with the analysis of loads ( Force, torque/moment) on Physical systems in Static equilibrium It is important to note that the amount of work done is given by force times distance. In Physics, mechanical work is the amount of Energy transferred by a Force. In Physics, a force is whatever can cause an object with Mass to Accelerate. Distance is a numerical description of how far apart objects are 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). In mathematics the dimension of a Space is roughly defined as the minimum number of Coordinates needed to specify every point within it The lever only allows to trade force for distance.
Archimedes was the first to explain the principle of the lever, stating:
"(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 of Syracuse ( Greek:) ( c. 287 BC – c 212 BC was a Greek mathematician, Physicist, Engineer "
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
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:
- 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. A beam engine is a design of Engine based on the principles of a first-class Lever. e. D1 = D2)
- Bicycle hand brakes
- Can opener and bottle opener
- Crowbar (curved end)
- Curb bit
- Hammer, when pulling a nail with the hammer's claw
- Hand trucks are L-shaped but work on the same principle, with the axis as a fulcrum
- Oars
- Pliers (double lever)
- Scissors (double lever)
- Seesaw (also known as a teeter-totter)
- Shoehorn
- Spud bar (moving heavy objects)
- Trebuchet, an upside down example of the above picture
- Wheel and axle because the wheel's motions follows the fulcrum, load arm, and effort arm principle
Second-class levers
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. Bicycle brake systems are used to slow down or Brake a Bicycle. Churchkey or Church key can refer to various kinds of Bottle openers or Can openers History It initially referred to a simple hand-operated Varieties There are several distinct designs of such bottle openers A crowbar, pry bar, or prybar, more informally a jimmy, jimmy bar, jemmy ( British Isles) or gooseneck is A curb bit is a type of bit used for riding Horses that uses leverage A hammer is a tool meant to deliver an impact to an object The most common uses are for driving nails fitting parts and breaking up objects A hand truck (also known as a 2-wheel dolly, a stack truck, or a trolley or sack truck in the United Kingdom or a An oar is an implement used for water-borne propulsion. Oars have a flat blade at one end Pliers are Hand tools designed primarily for gripping objects by using Leverage. Scissors are hand operated cutting instruments consisting of a pair of Metal Blades connected in such a way that the blades meet and cut materials placed A seesaw (also known as a teeter-totter) is a long narrow board suspended in the middle so that as one end goes up the other goes down A shoehorn is a Tool that allows the user to put on a Shoe more easily A spud bar (in British Isles usually Crowbar or just bar) is a long straight metal bar used lengthwise as a Hand tool to A trebuchet or trebucket is a Siege engine that was employed in the Middle Ages either to smash Masonry Walls or to throw The wheel and axle is a Simple machine. The traditional form as recognised in 19th century textbooks is as shown in the image Examples:
- Dental elevator
- Door
- Nutcracker
- Paddle
- Springboard (diving board)
- Wheelbarrow
- Wrench
- Diving Board
- Crowbar (flat end)
- Push-up
Third-class levers
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:
- Arm
- Baseball bat
- Boat paddle
- Broom
- Chopsticks
- Door
- Fishing rod
- Hockey stick
- Tongs
- Tweezers
- Mandible
- Mousetrap
- Nail clippers, the main body handle exerts the incoming force
- Shovel (the action of picking or lifting up sand or dirt)
- Sling
- Tools, such as a hoe or scythe
- Stapler
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. In Anatomy, an arm is one of the Upper limbs of an animal The term arm can also be used for analogous structures such as one of the paired upper limbs A baseball bat is a smooth wooden or metal club used in the game of Baseball to hit the ball after the ball is thrown by the pitcher. A paddle is a tool used for pushing against Liquids either as a form of propulsion in a Boat or as an implement for mixing A broom is a Cleaning Tool consisting of stiff fibres attached to and roughly parallel to a cylindrical handle, the broomstick. A door is a panel or barrier usually hinged or sliding that is used to cover an opening in a Wall or partition going into a building or space A fishing rod or a fishing pole is a Tool used to catch fish, usually in conjunction with the Sport of Angling, can also be used in A hockey stick is a piece of equipment used in Field hockey, Ice hockey, or Roller hockey to move the ball or puck 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 They are probably derived from Tongs, Pincers The mandible (from Latin mandibula, "jawbone" or inferior maxillary bone forms the lower Jaw and holds the lower teeth in place A mousetrap is a specialized type of Animal trap designed primarily to catch mice; however it may also trap other small animals A nail clipper (also called a nail trimmer or nailcutter) is a mechanical device used to trim Fingernails and Toenails. A shovel is a Tool for lifting and moving loose material such as Coal, Gravel, Snow, Soil, or Sand and is an A sling is a projectile Weapon typically used to throw a blunt Projectile such as a stone Hoes are Bladed Tools used to agitate the surface of the Soil around Plants to remove weeds pile soil around the base For the ancient Sicilian tyrant see Scythes. A scythe (ˈsaɪð from Old English siðe. 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 A mnemonic device (nəˈmɒnɪk is a Memory aid Commonly met mnemonics are often verbal something such as a very short poem or a special word used to help a person remember (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.
See also
External links
- Lever at Diracdelta science and engineering encyclopedia
- A Simple Lever by Stephen Wolfram, The Wolfram Demonstrations Project. Applied mechanics is a branch of the Physical sciences and the practical application of Mechanics. Engineering vehicles, known by the other terms construction Equipment, earth movers heavy equipment or just plain equipment are machines specifically designed to execute A mechanical linkage is a series of rigid links connected with joints to form a closed chain or a series of closed chains In Physics, especially Mechanics, a simple machine is a mechanical device that changes the direction or magnitude of a Force. A switch is a mechanical device used to connect and disconnect an electric Circuit at will Archimedes of Syracuse ( Greek:) ( c. 287 BC – c 212 BC was a Greek mathematician, Physicist, Engineer Stephen Wolfram (born August 29, 1959 in London) is a British Physicist, Mathematician and Businessman known for his
- Levers: Simple Machines at EnchantedLearning. com
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