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| [[File:Balancedbeam.jpeg|right|thumb|200px|Beam balanced around a fulcrum]]
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| A [[simple machine]] that exhibits [[mechanical advantage]] is called a '''mechanical advantage device''' - e.g.:
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| * [[Lever]]: The [[Beam (structure)|beam]] shown is in static equilibrium around the [[wikt:fulcrum|fulcrum]]. This is due to the [[Moment (physics)|moment]] created by vector force ''"A"'' counterclockwise (moment ''A''*a) being in equilibrium with the moment created by vector force ''"B"'' clockwise (moment ''B''*b). The relatively low vector force ''"B"'' is translated in a relatively high vector force ''"A"''. The force is thus increased in the ratio of the forces ''A : B'', which is equal to the ratio of the distances to the fulcrum ''b : a''. This ratio is called the mechanical advantage. This idealised situation does not take into account friction.
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| * [[Wheel and axle]] motion (e.g. [[screwdriver]]s, [[doorknob]]s): A wheel is essentially a lever with one arm the distance between the axle and the outer point of the wheel, and the other the radius of the axle. Typically this is a fairly large difference, leading to a proportionately large mechanical advantage. This allows even simple wheels with wooden axles running in wooden blocks to still turn freely, because their [[friction]] is overwhelmed by the rotational force of the wheel multiplied by the mechanical advantage.
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| * A [[block and tackle]] of multiple [[pulley]]s creates mechanical advantage, by having the flexible material looped over several pulleys in turn. Adding more loops and pulleys increases the mechanical advantage.
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| * [[Screw]]: A screw is essentially an [[inclined plane]] wrapped around a cylinder. The run over the rise of this inclined plane is the mechanical advantage of a screw.<ref>Fisher, pp. 69–70.</ref>
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| ==Pulleys==
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| [[File:Four pulleys.svg|thumb|450px|Examples of rope and pulley systems illustrating mechanical advantage.]]
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| Consider lifting a weight with rope and pulleys. A rope looped through a pulley attached to a fixed spot, e.g. a barn roof rafter, and attached to the weight is called a ''single pulley''. It has an MA = 1 (assuming frictionless bearings in the pulley), meaning no mechanical advantage (or disadvantage) however advantageous the change in direction may be.
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| A ''single movable pulley'' has an MA of 2 (assuming frictionless bearings in the pulley). Consider a pulley attached to a weight being lifted. A rope passes around it, with one end attached to a fixed point above, e.g. a barn roof rafter, and a pulling force is applied upward to the other end with the two lengths parallel. In this situation the distance the lifter must pull the rope becomes twice the distance the weight travels, allowing the force applied to be halved. Note: if an additional pulley is used to change the direction of the rope, e.g. the person doing the work wants to stand on the ground instead of on a rafter, the mechanical advantage is not increased.
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| By looping more ropes around more pulleys we can continue to increase the mechanical advantage. For example if we have two pulleys attached to the rafter, two pulleys attached to the weight, one end attached to the rafter, and someone standing on the rafter pulling the rope, we have a mechanical advantage of four. Again note: if we add another pulley so that someone may stand on the ground and pull down, we still have a mechanical advantage of four.
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| Here are examples where the fixed point is not obvious:
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| * A velcro strap on a shoe passes through a slot and folds over on itself. The slot is a movable pulley and the MA = 2.
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| * Two ropes laid down a ramp attached to a raised platform. A barrel is rolled onto the ropes and the ropes are passed over the barrel and handed to two workers at the top of the ramp. The workers pull the ropes together to get the barrel to the top. The barrel is a movable pulley and the MA = 2. If there is enough friction where the rope is pinched between the barrel and the ramp, the pinch point becomes the attachment point. This is considered a fixed attachment point because the rope above the barrel does not move relative to the ramp. Alternatively the ends of the rope can be attached to the platform.
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| * [[Block and tackle]]: MA = 2 or more, depending on design (see above)
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| ==Screws==
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| The theoretical mechanical advantage for a screw can be calculated using the following equation:<ref>United States Bureau of Naval Personnel, p. 5-4.</ref>
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| :<math>MA = \frac{\pi d_m}{l}</math>
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| where
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| :''d<sub>m</sub>'' = the mean diameter of the screw thread
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| :''l'' = the [[lead (engineering)|lead]] of the screw thread
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| Note that the actual mechanical advantage of a screw ''system'' is greater, as a screwdriver or other screw driving system has a mechanical advantage as well.
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| * [[Inclined plane]]: MA = length of slope ÷ height of the slope
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| ==See also==
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| * [[Balanced arm lamps]]
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| * [[Gear ratio]]
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| * [[Simple Machine]]
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| ==References==
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| ===Notes===
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| {{reflist}}
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| ===Bibliography===
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| *{{Citation | last = Fisher | first = Len | title = How to Dunk a Doughnut: The Science of Everyday Life | publisher = Arcade Publishing | year = 2003 | url = http://books.google.com/?id=VuK7m3LU8rgC | isbn = 978-1-55970-680-3}}.
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| *{{Citation | last = United States Bureau of Naval Personnel | title = Basic machines and how they work | publisher = Courier Dover Publications | year = 1971 | edition = Revised 1994 | url = http://books.google.com/?id=yDKzy4rKEg0C | isbn = 978-0-486-21709-3}}.
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| ==External links==
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| * [http://www.technologystudent.com/gears1/geardex1.htm Gears and pulleys]
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| * [http://www.swe.org/iac/lp/pulley_03.html Mechanical engineering — pulleys]
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| * [http://ca.youtube.com/watch?v=yfAdmRJDKIc Mechanical advantage — video]
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| [[Category:Simple machines]]
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| [[Category:Mechanical engineering]]
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| [[Category:Mechanics]]
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| [[de:Kraftwandler]]
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| [[nl:Mechanische versterker]]
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| [[no:Gir]]
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| [[sv:Växel (maskinteknik)]]
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He hangs way up. The first person to call him in two days is a telemarketer. He grips his aluminum cane challenging he can check out calluses bite into his palms. The damned thing. He shouldn't even be on it anymore, but he is not doing his physical activity. No way in Hell should he have come back from a ten-day vacation with Type 2 Decompression Sickness. Off of a lousy 35-foot plunge.
Access internet mail and POP3/IMAP client email accounts as well from your G502 that will help Exchange ActiveSync for complete mobility. The RSS desktop makes sure you get the ugg news and updates belonging to the favourite websites on your phone. The G502 is often a sure update as it comes with 3G and HSDPA for serious download speed, which the G900 was lacking. Now, must need your personal machine to print your imagery. The G502 includes a PictBridge which makes it possible to print pictures straight fro your get in touch with.
When first receiving the pair of boots from any store, require to first determine that these boots are in brand new condition. Humorous never be too picky when purchasing ugg boots. When you discover it that these boots are in brand new condition, you can begin the caring process with regards to your boots.
Don't fail to remember internet to see good offers in websites too. Besides some of them create sales too, which will probably find really cheap boots. Recently make some quick homework using Google . com. Some of the stores via the net are selling fakes, therefore if the expenditure is just too low, search for become a negative offer.
First and foremost; handful of basic to possess a First-Aid tools. This will a person if someone suffers from injury. Bandages, alcohol, medicines and other medicinal supplies shall be included capable to aid you throughout the calamity. Then, you likewise require to have water. Components . to know that you can withstand every calamity with the help water. You require have your water that will help you to thrive. See into it that will certainly keep water for at least one gallon each new day.
If you are planning to obtain factory directly, make sure the company is authorized. Some manufacturers your family with sheepskin boots on incredibly cheap prices as those footwear is fakes. Therefore do research on official UGG websites before payment.
In the event you beloved this informative article as well as you desire to receive guidance with regards to cheap uggs factory outlet generously check out the web-page.