1. The problem statement, all variables and given/known I have been asked to calculate the minimum length of this column (attatched) at which buckling is likely to occur 2. Relevant equations E.S.R = sqrt(π^2*E / σ) 2nd moment of Area I = AK^2 E.S.R = L/K I= π/32*(D^4-d^4) 3. The attempt at a solution so E.S.R = sqrt(π^2*200*10^9 / 140*10^6) = 118.74 Since I = AK^2 and E.S.R = L/K L= (E.S.R)*K = (E.S.R)*sqrt(I/A) so I = π/32 * (0.08^4-0.06^4) = 2.75*10-6 Now L = 188.7 * sqrt(2.75*10-6 / Area) ive got that far but don't know a suitable equation for area, I'm not looking for answers just for someone who can tell me if I'm on the right track, any help would be appreciated!!