by Aerandirel
 P: 4 For an Intro engineering class we've working on a project to make bridges out of spaghetti. To determine if the different spaghetti components of my bridge are strong enough to hold the force that's being applied on them, Ive been trying to calculate the spaghetti's critical buckling load for the components in the bridge under compression. Im getting real whacky numbers when Ive been trying to calculate these forces. They arent matching up any where close to the compression strengths Ive measured in the lab. Alright so the equation I need to solve this is F = (pi^2)*(E)*(I)/(L^2), or Euler's buckling Load formula. E = young's modulus of elasticity, I = cross section moment of inertia, which Ive been told is = pi*(R^4)4 (R is radius). E for spaghetti is somewhere around 5 gigaPascals. Anyways, picking out one example from the data Ive collected I have a 10 cm long piece of past with a radius of .1 cm. The amount of force recorded when the spaghetti started to buckle during testing was 2.25 newtons, so I should get around this force when I use Euler's buckling formula right? Attempt -------- Ok so converting all measurement to meters I plug in F = [ (pi^2)*5*(pi*(.001m^4)/4) ] / .1 cm ^2. I work this out and get F = 3.87*10^-9 newtons....what am I doing wrong?
 Sci Advisor HW Helper PF Gold P: 6,035 Check your math and units. A GigaPaschal is (10)^9 Paschals.
 P: 4 Yes Ive checked a million times. Are you saying I should plug in the 5 GPA Youngs Modulus value into the equation as 5*10^9 instead of just 5? Ive done that too, and I still dont get the right Force values. Can anyone verify that im using the correct equation for this? Ive seen slightly different ones all over the internet. Again Im trying to calculate Critical Buckling Load for a piece of dry spaghetti in compression. And btw, this is more of a self pursued experiment then one I was assigned, so this isnt something straight of my homework or anything, im jsut trying to get a better understanding of how my bridge will hold up. Edit: Ok during testing I recorded a force of .9 Newtons in order to make the piece of spaghetti slightly buckle. By the Critical buckling formula I get a force of 3.5 Newtons. Is this reasonable for a max compression force for a 10 cm piece of dry spaghetti?
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