The external loads acting on the shaft in a gear system are given as Ma = 412.5 kN mm, Tm = 366,0 kN mm, Mm = Ta = 0. For the shaft the material 1020 CD steel is selected wchic has Sut = 470 MPa. Other knowns for the design are: K, = 1.7, Ks = 1.5, K= K, Kjs = Kis, a=3,04, b= -0,217, ko=0.9, ke = ka ke= 1, n=1,5. a) Calculate the schaft dimameter b) Calculate the safety factor according to the Goodmann ciriterion.