Euler's formula

A formula expressing the resistance of long columns to buckling:

<math> P = \frac{a \pi^2 EI}{l^2} </tex>

where

P = the external load or pressure

E = the modulus of elasticity

<math>I</tex> = the least moment of inertia

<math>l</tex> = length

a = constant depending on end conditions

<math>\pi</tex> = 3.14159