A straight steel alloy bar of thickness $4\mathrm{.}5$mm and width $12\mathrm{.}5$mm is axially loaded until

buckling occurs. Estimate the length of the bar when the yield load is $300$ MN$/$m$2,$ E $=70$

GN$/$m$2$ and the Euler buckling load is $90$N$.$ Calculate the slenderness ratio of the bar.