A solid round bar of $60$mm diameter and $2\mathrm{.}5$m long is used as a strut. Find the safe compressive load for the strut using Euler's formula if:

a$)$ Both ends are hinged. $/$

b$)$ Both ends are fixed.

Take E $=2*10^5*$ N $/$ m $*$ m $^2$ and factor of safety $=3$