1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Finding Lever Lengths With Overall Mechanical Advantage

  1. Sep 6, 2011 #1
    1. The problem statement, all variables and given/known data
    If the mechanical advantage of a lever is, lets 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 length of the effort/lever arm).


    2. Relevant equations



    3. The attempt at a solution
    Here's what I'm thinking.
    MA = 10
    Simultaneously,
    MA = Effort Arm / Load Arm
    10 = Effort Arm / Load Arm
    Load Arm * 10 = Effort Arm
    Load Arm + Load Arm * 10 = Effort Arm + Load Arm
    2Load Arm * 10 = 5
    2Load Arm = 5/10
    Load Arm = 0.5

    True or false?
     
    Last edited: Sep 6, 2011
  2. jcsd
  3. Sep 6, 2011 #2

    ehild

    User Avatar
    Homework Helper
    Gold Member

    It is correct up to here, but how did you get the following?
    1(load arm)+10 (load arm) = ? (load arm) ?

    If you add one apple to 10 apples will you get 2*10 =20 apples?

    ehild
     
  4. Sep 6, 2011 #3
    Then how would you isolate the load arm?
     
  5. Sep 6, 2011 #4
    11 * load arm = effort arm + load arm?
    load arm = effort arm + load arm / 11?
     
  6. Sep 6, 2011 #5

    ehild

    User Avatar
    Homework Helper
    Gold Member

    No, it is wrong. Division by 11 in your formula refers to the load arm only.
    Use parentheses: length of load arm =(length of effort arm+length of load arm)/11, that is, 5/11 m.

    Remember the hierarchy of operations: First perform everything in the parentheses. Otherwise perform multiplication/division first then the addition/subtraction.

    ehild
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Finding Lever Lengths With Overall Mechanical Advantage
  1. Mechanical advantage (Replies: 10)

  2. Mechanical Advantage (Replies: 2)

  3. Mechanical Advantage : (Replies: 1)

  4. Mechanical advantage (Replies: 4)

Loading...