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!

Optimising Support Location - Bending moments

  1. Mar 23, 2013 #1
    1. The problem statement, all variables and given/known data
    Firstly, I know posting images and asking for help is generally frowned upon, however in this case given the number of diagrams and equations involved I'm hoping it's warranted.

    So we're given a diagram as at the top of the attached image and we're asked, given most of the unknowns, to find at what value of 'L3' reaction force no. 2 should be located such that the maximum bending moment is minimised.

    2. Relevant equations
    sum of forces = 0
    sum of moments = 0


    3. The attempt at a solution
    see attached image - I have written it out in terms of parameters, however I am at a loss of how to find R1, R2, and L3.. there seems to be too many unknown variables. Any hints would be appreciated.
     

    Attached Files:

    Last edited: Mar 23, 2013
  2. jcsd
  3. Mar 23, 2013 #2

    SteamKing

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    First, take your equations of static equilibrium and substitute the known values of the quantities given. You will have one unknown value, namely L4, which you will use in optimizing the maximum bending moment. You should be able to express R1 and R2 in terms of L4. This will simplify you problem greatly.
     
  4. Mar 23, 2013 #3

    SteamKing

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    Substitute L3 for L4 in the post above.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted