An aluminum pipe column (alloy 2014-T6) with pinned ends has outside diameter D2 = 120 mm and

Question:

An aluminum pipe column (alloy 2014-T6) with pinned ends has outside diameter D2 = 120 mm and inside diameter d1 = 110 mm (see figure).
Determine the allowable axial load Pallow for each of the following lengths: L = 1.0m, 2.0 m, 3.0 m, and 2.0 m.
(Convert the given data to USCS units, determine the required quantities, and then convert back to SI units.)