A $5$m long cantilever beam of rectangular cross section is subjected to vertical $($shear$)$ force of $10$KN applied at its free end. The height of the beam$$s cross section is $5$ times its width $($h $=5$b$).$ Determine h and b if the beam is to resist yielding under the applied stress condition. Assume the beam is made from a material whose yielding limit is $200$MPa