The steel bar $A B$ has a rectangular cross section. If it is pin connected at its ends, determine the maximum allowable intensity $w$ of the distributed load that can be applied to $B C$ without causing bar $A B$ to buckle. Use a factor of safety with respect to buckling of $1.5 . E_{\mathrm{st}}=200 \mathrm{GPa}$ $\sigma_{Y}=360 \mathrm{MPa}$