Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Load bearing structure made of matchsticks

  1. May 18, 2008 #1
    1. The problem statement, all variables and given/known data
    Ok, i have a small (optional) project, to design a load bearing structure made of matchsticks. The structure must be able to withstand the load a computer monitor (i have a 17" one).
    2. Relevant equations
    Now, the problem i am facing is how would the force (of gravity due to the mass of the monitor be distributed across the matchstick structure?
    Note that, i intend to make use of 'matchstick trusses' (only two force members), with 'pin joints' (actually strings binding the match sticks).
    3. The attempt at a solution
    I am actually totally clueless about this, as the problems i had encountered in high school assumed that all the weight acted through the centre of mass, which i don't think would be a valid assumption given the apparent non uniform distribution in the monitor.
  2. jcsd
  3. May 19, 2008 #2
    ok...i know i wasn't much specific, but anyone???

    maybe to elaborate a little, i want to find the transmission of forces at the monitor-structure interface.
    Am i right to assume that the weight actually does act thru the centre of mass (approx) and then find the reaction of supports thru moments at each point of contact?
  4. May 19, 2008 #3


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    I don't know what your monitor (or truss) looks like, but my monitor is a flat 17 " screen supported on a round base about 9" in diameter, and it's load is supported pretty much uniformly at the base. In any case, in determining support reactions on your truss, you can do this by placing the monitor weight at the center of mass of the monitor, and determine the reactions by the static equiilibrium equations. However, in determining member forces, you should distribute the weight to the top joints beneath the monitor support as concentrated loads at those joints. You probably don't have to worry about truss member bending in between the joints since the monitor base is much more rigid than any individual truss member, so you still will only get axial loads in your members.
  5. May 20, 2008 #4
    thanks a lot!!!
    actually mines not a LCD, or any of the new types...its big and heavy, but i do get your point!

    Thanks again!
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook