A $50mm$ diameter solid shaft is welded to a flat plate. If the size of the weld is $15mm$ find the following:

a$)$ Calculate the total throat area of the weld $(m{m}^2).$

b$)$Calculate the primary shear stress in the weld $($MPa$).$

c$)$Calculate the secondary shear stress in the weld $($MPa$).$

d$)$ Which welding electrode should the engineer use in this design?