The torques shown are exerted on pulleys C, B, and A. Knowing that the entire shaft is made of cast-iron (G= 140 GPa), determine the following: (a) The shaft in which the maximum shearing stress occur and it magnitude. (b) The angle of twist between A and B, where the length LAB = LCD = 0.4 m. (c) The angle of twist between B and C, where the length LBC = 0.6 m. 144 N-ma 48 N-ma 60 N-m den-21 mm de 18 mm dan-15 mm