$(2)$ A solid round bar of $60$ mm dlameter and $2\mathrm{.}5$ m long is used as a strut. find the maximum compressive lond the strut can sustain if $($i$)$ both ends are hinged $(11)$ both ends are fixed.

Take $E=2{10}^5\frac{N}{m}{m}^2$

Safety factor $=3\mathrm{.}0$