What is Lever: Definition and 177 Discussions

A lever ( or US: ) is a simple machine consisting of a beam or rigid rod pivoted at a fixed hinge, or fulcrum. A lever is a rigid body capable of rotating on a point on itself. On the basis of the locations of fulcrum, load and effort, the lever is divided into three types. Also, leverage is mechanical advantage gained in a system. It is one of the six simple machines identified by Renaissance scientists. A lever amplifies an input force to provide a greater output force, which is said to provide leverage. The ratio of the output force to the input force is the mechanical advantage of the lever. As such, the lever is a mechanical advantage device, trading off force against movement.The formula for mechanical advantage of a lever is



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{\displaystyle Load/Effort}

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  1. T

    Calculating torque when the lever arm has mass

    Homework Statement A board is set on top of a scaffolding, with dimensions as shown in the diagram. The board weighs 15 kg. A man weighing 70 kg stands on the board as shown. How far out can he stand before the board falls? Homework Equations Torque: \tau = rFsin(\theta) Force due...
  2. B

    Lever with spread load: formula

    Hi Guys, How much force will I need to lift 5000 kg block and how much force will be acting on the pivot point? I know how to calculate a normal lever but couldn't find any formula for lever with load evenly spread as per the attached diagram. see the attached diagram Thanks
  3. K

    Calculation of clutch lever ratio

    Hi, I recently got an opportunity to work on a clutch assembly. The clutch is an old model one which has six helical springs that keep pressing the pressure plate, clutch plate and engine flywheel against each other. The cross section is: To give a brief working principle, when the...
  4. A

    Help balancing an unequal lever thru an arc - (Foldover flagpole)

    I am constructing a pipe flagpole that instead of using a rope or wire to run the flag up, has a pivotrod or axel near the bottom (fulcrum point) that allows the entire pole to be pulled down when unlocked. The Idea is that you attach a piece of chain a ways up the pole and use it to pull the...
  5. S

    Weight increase on a lever as distance from body increases

    Homework Statement very 'uninformed' person here please bear with me. this relates to a piece of work equipment that i use but am not comfortable doing so. a 6" aluminum rod that weighs 6# is extended from its vertical away from the body to reach a 'target' from 4' to 6' away. the rod will...
  6. J

    Velocity Ratio and Lever Confirmation

    Homework Statement Calculate the velocity ratio of the attached lever. Homework Equations Velocity Ratio = Distance moved by effort * Distance moved by load The Attempt at a Solution Ok I'm having some confusion over this question. I cannot figure out whether the 'Distance...
  7. V

    Why is is easier to push a heavy load on wheels with a short lever

    Why is it easier to push a load on a wooden crate on wheels when you are nearer the load and the lever is shorter and at a sharp angle compared to pushing a load with the lever lengthened and at a more relaxed angle with your body further away?
  8. J

    What Calculations Are Needed to Solve This Third Order Lever Problem?

    Homework Statement The 200Kg Crates are placed on a hydraulic lifting beam: (Diagram attached) A. State the order of lever used here B. Calculate the effort required to lift the load C. Calculate mechanical advantage for this system D. Calculate the velocity ratio for this system. If the work...
  9. P

    Lever Formula: F*a=Q*b or Q*a=F*b?

    Is the lever formula ##F*a=Q*b## or ##Q*a=F*b## is it the same thing ? thanks
  10. J

    Calculating Torque and Horsepower with Levers

    If I have a 10 foot long lever and the fulcrum is 1 foot from the end, if I place 2000 lbs. of force on the lever, what will be my "force" or torque at the end of the lever? And, very important, how much distance will the tip of the short end of the lever move up if the long end of the lever can...
  11. K

    Why does a Lever arm magnify force?

    Hey, I'm looking for an explanation of the why we observe T = F * d In the sense of two people applying a force to a lever arm and the person closer to the pivot point requiring more force to keep the torque in equilibrium. I can only find explanations in the sense of work and energy...
  12. C

    Lever with offset pivot problem

    Homework Statement I have a situation a shown in the diagram below. A lever with a gas compression spring opposing it's turning. I want to find the force acting on the spring, F1, for a given inital force @ F0. [PLAIN]http://img18.imageshack.us/img18/9830/lever01.png Homework...
  13. B

    Can a Lever Class Change During Rotation?

    Is it possible for a lever to change from one class to another during its rotation (e.g. it starts out as a third class lever and ends as a first class lever)?
  14. W

    Mechanical Advantage of a Lever

    Homework Statement If a lever has a mechanical advantage of 0.5 - does this mean the input force is not amplified but halved? Homework Equations The Attempt at a Solution
  15. W

    Finding Lever Lengths With Overall Mechanical Advantage

    Homework Statement If the mechanical advantage of a lever is, let's say, 10; the forces pushing down on the effort arm equate to 100kg and the forces pushing down on the load arm equate to 1000kg and the lever itself is 5 meters, how do we go about finding the individual arm lengths (i.e. the...
  16. J

    How Do You Calculate the Effort Required in a Lever System?

    Homework Statement Calculate the effort required to lift the load. Homework Equations F=mg large distance × small effort = small distance × large load The Attempt at a Solution The load of the crate= F=mg F=200*9.81 F=1962N large distance × small effort = small distance...
  17. R

    How to optimize this lever mechanism

    I have a friend who has a small workshop and he's looking to build a mechanism to help him burn the oil off metal parts(don't ask why, that's all he said and I could be bothered asking), So far he's got a decent gravity fed system that cleans the bearings and then passes them on to this...
  18. A

    Master the Lever Rule: Tips and Tricks for Understanding this Important Concept

    Could someone please help me on this question. I do not really understand how to use the lever rule. Attactched is an example.. Thanks very much
  19. A

    Velocity Ratio of a 3rd Class Lever

    Homework Statement 1962N Load 5 m from effort (hydraulic ram) and fulcrum 1m from effort. Calculate the Velocity ratio, if work input is 3000j calculate work output. Homework Equations VR = distance moved by effort / distance moved by load effort = 11772N MA = load / effort =...
  20. A

    Effort Required to lift a load using third order lever

    Homework Statement Calculate the effort required to lift a load of 1962N using a third order lever with load 5m distance from effot and fulcrum 1m distance from effort. Homework Equations i used the following, large distance x small effort = small distance x large effort The...
  21. D

    Lever / Fulcrum / counterbalance

    Please forgive my ignorance, math was never my strong suit. But I have a question that has been bugging me, and I can't seem to figure it out, and thought perhaps that someone here could easily answer my question. I am a fly fisherman, and have been investigating certain claims regarding a...
  22. O

    Real Life Third Class Lever Problem

    I am looking at building a pair of third class levers out of materials found at the local hardware store to lift up some 500lb and 1500lb hulls. I have systematically gone through every option available to move these hull pieces out of the mold and I'm left with two: 1) Modify an "off the...
  23. R

    Velocity ratio of a third class lever

    Homework Statement 3rd class lever 5m distance from load to effort and 1m distance from effort to pivot. Load = 1962 Effort required to lift load = 11772N MA = 0.16 or 1/6 ( so there really is no MA) Calculate the velocity ratio of the system ? Homework Equations I have...
  24. O

    Finding unknown mass using a lever system

    Homework Statement We have a lever system. The end of the left side is a distance w1 from the pivot. The end of the right side is a distance w2 from the pivot. When no masses are attatched the lever is touching the ground on the left side. We place a known mass called m1 on the far left side...
  25. J

    How does the math for lever forces work in this scenario?

    Point A Point X 11 pounds 5 inches 5 inches ↑ 5 inches 5 inches _________________________________________________________________ 2 pounds 8 pounds ↓ ↓ Assume the horizontal line is a rod that is 20 inches long. The 11 pounds upward force is from a cable tied to...
  26. S

    Non-Linear Lever Examples: Get the Answers Here

    Firstly, this is a great forum! Maybe this is more of a mechanical engineering question, but ... Can someone help give me some examples of non-linear levers? I want to be able to stretch a rubber band with factored-increasing force. Like a reversed camber on a compound bow. I hope I...
  27. J

    Calculating Net Force: Lever with Two Fulcrums & Beam Hit at 7 Feet

    I am trying to figure out the net force of around a fulcrum (actually two fulcrums). For ease, assume the following hypothetical and ignore the weight of the beam itself in the calculations: There is a beam that is 21 feet long that is being lifted by a crane. The left end is at "0 feet"...
  28. J

    Lever Balance Displacement Calculation

    Hello I am trying to design a force balance lever system. Basically the initial state will in a force balance equilibrium. That is, there will be a mass m placed onto of the capacitor plate to keep the lever balanced. I will then ramp the voltage of the capacitor up, causing a force of...
  29. V

    Torque and segmented lever arms

    My question is: How do you calculate torque when the lever arm is segmented? I have drawn a simple diagram to try to explain what I mean. Does the fact that the weight is now closer to the axis shorten my lever arm, or is the lever arm = D due to the fact that 10lbs is still being applied to...
  30. S

    Calculating torque for a bent lever

    [PLAIN]http://img444.imageshack.us/img444/8218/diagram.gif to calculate the torque (N*x) which one is correct? the one on top, or below.
  31. S

    Hinged lever held by a string - Problem regarding forces

    [PLAIN]http://img20.imageshack.us/img20/7673/lever.gif I've come upon this phenomenon that as you shift the load left, or right, or anywhere along the lever, the intersection of the directions for the contact force due to the wall and the tension from the string will always be directly above...
  32. P

    Speed of Lever at Rest w/ 3lb Weight Attached

    So I have a simple lever that is connected to an extension spring. When the extension spring is exteneded it applies a force of 40lbs on the lever. The lever is 3 feet long and the pivot point is 1 foot from the top and 2 foot from the bottom. The lever weighs 2.1 lbs and has a 3lb weight...
  33. S

    Force applied by someones hand on a lever

    I am redesigning a bicycle wheel quick release lever for a design project. I am trying to put together a force diagram as part of the project and I need to know the average force someones hand could apply to the tip of the lever to calculate the force exerted on the locking mechanism. Could...
  34. D

    What is the lenght of the lever arm? (when torque and force are given)

    Homework Statement If a torque of 55N.m is required and the largest force that can be exerted by you is 135N, what is the length of the lever arm that must be used? Homework Equations Lever Arm=(r)(sin) Torque=(Force)(r)(sin) The Attempt at a Solution To be honest, I'm stumped
  35. J

    First Post: Looking for an electric lever.

    Does anyone know of anything that flips a little lever when you send a current through it, then flips it back when you stop sending current? Something like this: _____ No current: _/ _ Current: \_____ _____ No current...
  36. J

    First Post: Looking for an electric lever.

    Does anyone know of anything that flips a little lever when you send a current through it, then flips it back when you stop sending current? Something like this: _____ No current: _/ _ Current: \_____ _____ No current...
  37. J

    Hydraulic Lever: Effect of Force on Pressure

    I have a doubt about hydraulic lever if a force f1 is applied at piston of smaller area a1 then pressure is transmitted to every part of fluid due to aplication of f1 smaller piston move down and piston at other end move up does the moving up of second piston have any effect on...
  38. E

    Torque Of Lever Arm in 1st/2nd Class Levers

    Part 1 - Question About Torque Of Lever Arm in a 1st Class Lever Homework Statement A little while back I posted a question about incorporating the torque of a uniform mass and dimension lever arm into the principle of a 1st class lever. Here is the thread for reference...
  39. E

    What Is The Complete Formula Of A Lever?

    In trying to solve a problem, I was using the simple F1D1 = F2D2 as the balance point of a lever. My limited physics knowledge knew no better. My hypothetical involved using the "short side" of a lever to lift a weight on the long side of a lever. After thinking about it... I realized I...
  40. K

    Determining maximum force applied on a lever

    Homework Statement The lever BCD is hinged at C and is attached to a control rod at B. Determine the maximum force \vec{P} which can be safely applied at D if the maximum allowable value of the reaction at C is 500 N. Here is a picture of the problem. It is number 4.20. "[URL...
  41. J

    Lever question when lever is angled

    Hello, I have a question about a see-saw / lever problem. Does this configuration I have shown here allow me to treat the system like a regular lever if I make the downward force at the horizontal point from the center to be the cosine of the angle? In this example the downward force on the left...
  42. D

    Momentum distribution in a first class lever

    http://img16.imageshack.us/img16/7028/tempqk8.png This is the second time I'm posting this; last time I was told that it was not explicit. The image consists of 3 masses, m1, m2 and m3, out of which m1 and m3 lies at rest while m2 is in motion in the direction of the arrow. When m2...
  43. D

    Momentum transfer in a first class lever

    We have a seesaw arrangement, a mass m3 supports the fulcrum, we have mass m2 on one end, and a mass m1 fall on the other end with velocity v. Considering the distance between the fulcrum and m1 is d and that of m2 is r, what will be the momentum distribution?
  44. G

    How masses are added together on a lever

    lets say we have a balance with these masses attached: 1) 11g mass at 7cm to the left of the fulcrum 2) 32g mass at 16cm to the left of the fulcrum 3) 11g mass at 7cm to the right of the fulcrum 4) 32g mass at 16 cm to the right of the fulcrum This balance should be...
  45. R

    Lever system with a moving mass

    Hi all, I thought of an interesting problem that I don't know how to approach (it's been 8 years since my last physics class in undergrad studies). Here is a crude depiction of the problem: _____■_____ _____●_____ lever ....↑....... ground Assume the cube and sphere...
  46. Z

    How to remove mechanical advantage from a lever

    I have a simple lever with two points of equal force, each at a different distance from the fulcrum. --- What I want: As the arm turns, one point of force moves at a faster rate than the other. --- What I DO NOT want: One point of force having a mechanical advantage over the other...
  47. A

    Solving the Problem: Lever & Metal Wedge in Water

    hi.. i have a problem that i need to solve.. in the attached mage, there is a submerged object in water cousing na upward lift force of 100kg. above it is a lever with a weigh attached to it weighing at 90kg. wll this weight difference be enough to move the metal wedge from point a into point...
  48. Y

    A new angle on the Right Angle Lever Paradox.

    Right angle lever paradox. This paradox has long been a thorn in the side of relativity. In 1909 Lewis and Tolman analysed the behaviour of a right angled lever with balanced forces with relative motion. They noticed there would be a potential imbalance as the arm parallel to the direction of...
  49. C

    Mastering Lever Mechanics for MCATs to Understanding Net Torques

    Hi guys. I haven't had physics in a couple of years and I'm trying to study for the MCATs. I've always had trouble with levers so I would really appreciate it if I could get some help. In particular, the following scenario confuses me: Say you have a man standing on a board, the fulcrum is to...
  50. A

    Constructing a Crank and Slotted Lever Mechanism in 3 Days

    hey i have got to make a scaled model of any mechanism that we see around(or maybe we don't sometimes) in the machine shop in under 3 days as our summer training project. we are provided with all the raw stuff and machines that one usually sees in machining shop. i have decided to make a crank...
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