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Set up stations or give students a collection of Levers to try. They can use worksheets to record what class of Lever, or location of Fulcrum and forces, at each level. Class 1 Levers: Fulcrum is in the middle of one rigid rod, Force in is at one end of the rod and Force out is at the other end. Scissors cut paper claw hammer, removing nails from wood hole punch Clothes peg Tongs can opener Class 2 Levers: Fulcrum is at one end of the lever arm. Force in is at the other end of Lever arm. Force out is in the middle of Lever. Nutcracker and nuts Garlic press pop bottle opener Class 3 Levers: Fulcrum is at one end. Force in is in the middle. Force out is at the other end, and the end moves further with less force. Stapler Tweezers Tongs, chopsticks, Stapler remover Shovel with more space and / or outdoors, add tools from garden / woodshop: broom, wheelbarrow, Shovel, rake, crowbar, wrench, hedge clippers see saw is Class 1 Lever. Hockey sticks, baseball bats and many other sports equipment are Class 3. One end of the lever moves over greater distance but with less force, while the other end of the lever moves less far, but with greater force. Class 1 and 2 Levers, we generally move force at the end of the lever over larger distance, but little force is require, while at the other end of the lever, it does not move so far but with a lot of force - enough force to punch a hole or crack a nut. Class 3 Levers, we generally move Force in / effort end of Lever less far but with greater force, while the other end moves further but with little force, so allowing control, fine movements to pick up materials.
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The ability of the body to both apply and withstand forces is known as strength. One component of strength is the ability to apply enough force to move, lift or hold object with weight, also know as load. A lever is a rigid object used to make it easier to move large loads short distance or small loads large distance. There are three classes of levers, and all three classes are present in the body. For example, forearm is 3 Class level because the biceps pulls on the forearm between joint and ball. To see these body levers in action, check out this short video animation identifying levers in the body. Using the standard terminology of levers, forearm is Lever, biceps tension is effort, elbow joint is Fulcrum, and ball weight is resistance. When resistance is caused by the weight of an object, we call it load. Lever classes are identified by relative location of resistance, Fulcrum and effort. First Class levers have Fulcrum in the middle, between load and resistance. Second Class levers have resistance in the middle. Third class levers have effort in the middle.
Mechanical advantages of a machine characterize its ability to do work efficiently and effectively. Therefore, anytime simple machine is considered for appropriate engineering system, it is necessary to determine its associated mechanical advantage. In Lesson 1 of this unit, mechanical advantage of machine is defined as the ratio of Load to Effort. Mechanical Advantage is a way to determine how well a machine is performing. This idea can also be expressed by general mathematical equation: for three simple machines in this lesson, it is important to clarify what the mechanical advantage of a machine reveals about its capabilities. If MA = 1, this implies the machine has no effect on alleviating work, since output force is exactly the same as input force. Most simple machines provide a mechanical advantage greater than 1 so that work is made easier; ie, input force is increase, and therefore, mechanical advantage is less than output force. There are some cases when it is beneficial to have a mechanical advantage of less than 1. On this occasion, work is made harder by machines since input force is greater than output force. This may seem contrary to the purpose of simple machines; However, force must be reduced by machine in order for distance to be magnify. This is sometimes very useful in certain engineering applications and is surprisingly common among the three machines discussed in this lesson. To summarize this concept, If MA < 1, distance is multiplied, work is made harder, but faster; If MA > 1, Force is multiplied, work is made easier, but slower. With this information, engineers can modify mechanical advantages of machine in order to produce effective, efficient, and very useful appliance. The advantages of levers, which relate to effort and load, depend on how far away each are from Fulcrum. The mechanical advantage of Lever increases when either effort is moved further away from Fulcrum or the load is shifted closer to Fulcrum, or both. This idea of leverage can be expressed mathematically by: in this equation, distance between Load and Fulcrum is called Load Arm, while distance from Fulcrum to Effort is called Effort Arm as shown in Figure 9. Figure 9. Mechanical Advantage of levers. Copyright Copyright 2006 Jake Lewis, ITL Program, College of Engineering, University of Colorado Boulder notice that a single definition for mechanical Advantage of Lever applies to all three classes of levers. However, because of the physical arrangement of each lever type, we note that for second - class levers, MA > 1, and for third - class levers, MA < 1. First - Class levers have a unique option to magnify either input force or input distance. Capabilities of these different level types provide engineers with an array of choices during the design and selection process of a particular engineering system.
A lever is a bar or board that rests on support call fulcrum. Downward force exerted on one end of the lever can be transferred and increased in upward direction at other end, allowing small force to lift heavy weight. All early people used levers in some form, for example, for moving heavy stones or as digging sticks for land cultivation. The principle of lever was used in swape, or shadoof, long lever pivot near one end with a platform or water container hanging from the short arm and counterweights attached to the long arm. Man could lift several times his own weight by pulling down on long arm. This device is said to have been used in Egypt and India for raising water and lifting soldiers over battlements as early as 1500 bce.
A lever is a type of simple machine, which creates mechanical advantage to perform tasks by changing the magnitude and / or direction of forces. Lever needs Fulcrum, which is the central pivot for system to manipulate forces. Lever also needs some sort of rigid bar or rod placed in some position on Fulcrum to be functional. While levers may seem magical in that they change how much force is needed to do work, don't change work or energy needed. Like all simple machines, people use physics of levers to their advantage, but there's trade off for using less because force must be applied over greater distance. Many everyday tools use levers and fulcrums in their use, such as nail clippers, pliers, scissors, wheelbarrows, fishing rods, crow bars, and nutcrackers, just to name a few. Principles behind levers can also be explored by seeing how hard of push is needed to open a door at different distances from its hinges.
Today, role of large levers has been taken over by hydraulics and motors. Rather than finding manpower to apply great force to one side of the lever in order to slowly lift, it is easier to use motors and pistons. Modern day solutions have capabilities to lift loads straight up, which means that all of the effort that is put into lifting weight higher up. Effort put into Levers moves the load diagonally, meaning that more effort had to be put in in order to raise the load to the same height. However, as shown above, many everyday aiding objects are Levers. In fact, parts of our bodies act as Levers constantly. Although Levers have been surpassed for large projects, it seems that for common people le
You dont convince people by challenging their longest and most firmly held opinions. You find common ground and work from there. Or you look for leverage to make them listen. Or you create an alternative with so much support from other people that opposition voluntarily abandons its views and joins your camp. Ryan Holiday, Obstacle Is Way Roger J Volkema provides an example of how people use leverage for their own benefit in negotiations: this tactic is used commonly by businesses. Buying a drink or snack on airplane will always be expensive because airlines know people lack alternative,s giving them leverage. Spotify and Youtube can subject users to endless advertisements because services are otherwise free and this gives them control. Companies with monopoly can charge more because they own a particular market. Doctor can present extortionate bills because we have no option to return service. Volkema goes on to explain key principles of leverage: in one of his iconic letters to shareholders, Warren Buffett declare: Dont ask the barber whether you need a haircut. To do so transfers leverage to the barber, who will always say yes. To retain leverage would necessitate telling the barber you certainly do not need a haircut, leading them to offer you an attractive deal. Anyone who has ever haggled at market or with a salesperson will understand the principle of using leverage in negotiation. The trick is to declare their product or service to be so flawed and worthless that you are doing them a favor by buying it. Subsequently, next step is usually to offer a low price which they counter with a slightly higher one that is still much lower than the asking price. Another amusing example of leverage in negotiation comes from Jarod Kintz:
A good place to begin understanding the concept of leverage is the etymology of the word. We can trace its origins back to the Proto - Indo - European legwh which describes something light, agile, or easy. From this, Latin levare form, which refers to something that is not heavy. But the word absorbed into English in the 14th century from Old France where levier refers to raising something, so in essence, leverage refers to making something light by raising it in a specific manner. The fusion of these two ideas perfectly describes physical lever - pole connect to a fulcrum which serves to create additional strength or force. Lever do not bend or create additional friction. Levers with fulcrum in middle. Force is applied on one side and load is on the other side levers where load is placed in the middle and force is applied on one side, with fulcrum located on other levers where force is applied in the middle. Archimedes is credited with establishing the concept of leverage, over 2000 years ago. He famously stated that, give lever long enough and enough distance, he could lift the earth. In on Equilibrium of Planes, Archimedes write: Magnitudes in Equilibrium at distances are reciprocally proportional to their weights. However, Peripatetic School wrote of levers before the birth of Archimedes. In Mechanica, work believed to have been written by members of this School of thought, they state: like many of our mental models, leverage is a scientific concept which has applications in many other areas. Leverage is an idea which humans have used to great effect for thousands of years, enabling them to gain disproportionate strength. For example, ancient Egyptians used levers to lift stones weighing up to 100 tons in order to build pyramids and obelisks. Many of humanity's tools, used for centuries all over the world, incorporate levers - scissors, pliers, door handles, wheelbarrows, fishing rods and more. The concept of leverage has been applied to other areas over the last century or so. In Decision Making, Alan C McLucas defines leverage and leverage points as:
For all levers, effort and resistance are actually just forces that are creating torques because they are trying to rotate lever. In order to move or hold load, torque created by effort must be large enough to balance torque caused by load. Remembering that torque depends on the distance that force is applied from pivot, effort needed to balance resistance must depend on distances of effort and resistance from pivot. These distances are know as effort arm and resistance arm. Increasing effort arm reduces the amount of effort needed to balance load torque. In fact, ratio of effort to load is equal to the ratio of effort arm to load arm:
|3rd||Range of Motion The load moves farther than the effort. ( Short bicep contraction moves the hand far )||Effort Required Requires larger effort to hold smaller load. ( Bicep tension greater than weight in hand )|
|2nd||Effort Required Smaller effort will move larger load. ( One calf muscle can lift entire body weight )||Range of Motion The load moves a shorter distance than the effort. ( Calf muscle contracts farther than the distance that the heel comes off the floor )|
|1st (effort closer to pivot)||Range of Motion The load moves farther than the effort. ( Head moves farther up/down than neck muscles contract )||Effort Required Requires larger effort to hold smaller load.|
|1st (load closer to pivot)||Effort Required Smaller effort will move larger load.||Range of Motion The load moves shorter distance than the effort.|
Definitions Resistance Arm: Distance between axis and point of resistance application. Force Arm: Distance between axis and point of Force. Formula example: Lever characteristics Long Resistance Arm: speed and range of movement Short Resistance Arm: Force Mechanical advantage Motive Force Arm length / Resistive Force Arm length No Mechanical advantage If quotient = 1: If quotient > 1: Mechanical advantage in Force If quotient < 1: Mechanical advantage in speed and range of motion Lever length of Resistive forces Center of gravity of body segment Center of gravity of any additional weight. Perpendicular Distance from fulcrum When calculating forces applied to levers, Perpendicular Distance from fulcrum needs to be measure. Torque = Force x Perpendicular Distance. Physical distance and perpendicular distance are same only when force is being applied at the right angle to the lever. Perpendicular Distance can be calculated by multiplying physical distance x sine of angle of Force application. Also see Force Vectors and example below.
Force is place between axis and resistance examples: tongs: food is supported by grip on handles while the axis is at the opposite end. Shovelling: dirt on shovel is lifted by force to handle by hand while upper hand on end of shovel handle serves as axis rowing: oar is moved through water by pulling on middle of oar while holding end of oar with the opposite hand. Note: shovelling and rowing actions can also be first class lever systems if hand closes to force remains stationary and hand on far end of shovel or oar is move. Batting: ball is hit by moving the bat toward the ball with the hand of far arm while supporting the lower portion of the bat with the hand of near arm. Example in body most levers in the body are third class elbow flexion Biceps and brachialis pull ulna lifting forearm, hand, and any load at elbow. Knee flexion hamstring contract to flex lower leg at knee. Lever characteristics produce speed and range of motion require relatively great force to move even small resistance weight machines: less resistance require, greater inertia harder to start and stop movement.
The pivot is at the elbow and the forearm acts as a lever arm. Biceps muscle provide effort and bend forearm against the weight of the forearm and any weight that hand might be holding. Load is further away from pivot than effort. There is no mechanical advantage because effort is greater than load. However, this disadvantage is compensated with larger movement - small contraction of the biceps produces large movement of the forearm. This type of lever system also gives us the advantage of much greater speed of movement. Many muscle and bone combinations in our bodies are of the Class 3 level type.
Levers are simple machines that can be used to increase input force to lift or put pressure on objects, called loads. All levers have a few components in common: arm, straight inflexible part, and fulcrum, or pivot point on which the lever rests and pivots. Basic Lever is see - saw, where board on which people sit is arm, pivot on which board sit is fulcrum, and the contact point of see - saw with ground is load. Torque is a combination of distance and force, and higher torque allows a greater amount of work to be done Three different types of levers exist, depending on where input force, fulcrum, and load are. Class 1 Lever has fulcrum between input Force and load. Class 2 Lever has load between fulcrum and input Force. Class 3 Lever is a lever that has input force in between fulcrum and load.
By about 200 BC, scientists like Archimedes were beginning to figure out why levers work. These scientists saw that lever lets you do a lot of easy work instead of doing little bit of hard work. If youre trying to lift heavy rock one foot off the ground, you might not be able to lift it at all. But if you have a lever - long stick - you can get a mechanical advantage. You can push the lever down pretty easily, but you have to move it down four feet in order to lift the rock one foot. Youve do a lot of easy work instead of little hard work. It same amount of work, in the end, but spread out more.
Lever consists of a rigid beam that moves across hinge or fulcrum. Lever was identified as a simple machine by Archimedes, along with pulley and screw. Archimedes is often quoted as saying " Give me a place to stand and I will move Earth. Levers can exert large force over a small distance at one end by exerting small force over a large distance at the other. Ideal level do not lose or store energy, so power in is equal to power out. This relationship can be used to calculate mechanical advantage as ratio of distances from fulcrum for effort and load. It is impossible to say who invented the lever. Levers have been used throughout history to lift heavy objects that humans would otherwise not be able to lift. They were used by ancient Egyptians to move heavy blocks during the construction of the pyramids. Levers are still used in construction today, like when builders remove nails using claw on claw hammer, but are also used in many facets of everyday life.
Levers are one class of simple machines. Their operation depends on relative positions of load; pivot, call fulcrum; and apply effort. To maximize applied effort, most effective placement of fulcrum was found to be close to load. The Principle of leverage can be derived using Newton's laws of motion, and modern static It is important to note that the amount of work done is given by Force times distance. To use Lever to lift a certain unit of weight with an effort of half unit, distance from fulcrum to spot where force is applied must be twice the distance between weight and fulcrum. For example, to halve the effort of lifting weight resting one meter from the fulcrum, we would need to apply Force two meters from the other side of the fulcrum. The amount of work do is always the same and independent of the dimensions of Lever. Life only allows one to trade effort for distance.
How it work: If one end of the lever is pushed down, force will lift the other end. If the other end has a load on top of it, it will be easier to move the load. Lever makes work easier. Think of boy and girl on see saw. A boy may not be able to lift a girl up in the air using just his arms. On see saw, though, girl is sitting on one end and then boy can easily push down on other end and lift girl. This is exactly how see saw works, two people using force to move each other up into the air. There are actually three different classes of levers. Class level depends on the location of Load, Force, and Fulcrum. Some examples of levers include more than one class, such as nut cracker, stapler, nail clippers, ice tongs and tweezers. Other levers, called single class levers, include the claw end of a hammer. When pulling nail, nail is Load, Fulcrum is the head of the hammer, and Force is at the other end of the handle, which is Beam. Load and Fulcrum are close to each other, which makes it easier to remove nails with a hammer. Wheelbarrows, fishing rods, shovels, brooms, arms, legs, boat oars, crow bars, and bottle openers are all examples of levers. Levers may be one of the most used simple machine. As with all simple machines like lever, they are designed to help make work easier to do.
Lever is the simplest machine of all: it's just a long bar that helps you exert bigger force when you turn it. When you sit on see - saw, you ve probably figure out that you need to sit further from the balance point if the person at the opposite end is heavier than you. The further away from fulcrum you sit, more you can multiply the force of your weight. If you sit long way from the fulcrum, you can even lift much heavier person sitting at other endproviding, they sit very close to the fulcrum on their side. Force you apply with your weight is called effort. Thanks to fulcrum, it produces bigger force to lift load. Words effort and load can be very confusing, so we 've avoided using them in this article. An important thing to remember about levers is that the force you produce is bigger than the force you apply: with a long lever, you can exert a lot of leverage. When you use an axe or wrench, long handle helps to magnify the force you can apply. The longer you handle, more leverage you get. So, a long - handled wrench is always easier to use than a short - handled one. And if you can't budge nut or bolt with a short wrench, try one with a longer handle.
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