//consider an aluminium rod. 
D=6.35*10^-3;//diameter(meter) of the rod
T=11125;//Applied load(N) on the rod
Sty=3103;//yield tensile stress(bar)of aluminium rod
Stu=4206;//ultimate tensile stress(bar)of aluminium rod
sigma=T/(%pi*D^2*10^5/4) //tensile stress(bar) on the rod