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liamacky · May 15, 2012, 05:32 AM

can anyone transpose this equation for I

Pcr=(x2EI)/L2

ebaines · May 15, 2012, 05:57 AM

Originally Posted by liamacky

can anyone transpose this equation for I

Pcr=(x2EI)/L2

I'm guessing wjat you really meant to write tis this:

$ P_{CR} = \frac {x^2EI} {L^2} $

FYI - for future reference the convention for signifying a power is to use tke carat symbol ^, so x^2 would mean "x squared."

This formula looks a variation of the Euler critical load equaton, with the exception that you've placed an x^2 where there should be pi^2. No matter - to make 'I' the subject you need to do a series of operations that leaves 'I' by itself. First multiply both sides by the denominator of the right had side; this causes the L^2 term on the right to cancel:

$ P_{CR} \times L^2 = \frac {x^2EI} {\cancel {L^2}} \times \cancel {L^2} = x^2EI $

Then divide both sides by x^2E:

$ \frac {P_{CR} L^2} {x^2E} = \cancel{ x^2EI} \times \frac 1 {\cancel {x^2E}} = I $

liamacky · May 25, 2012, 12:39 PM

Thank you, excellent help, much appreciated.