3. There is a hollow aluminum shaft fixed from one end to a wall with an inner diameter of 0,012 m; outer diameter of 0,018m; the length of 1,25m (G=27 GPa). (a) If the shaft can twist max 4, calculate the torque. (15 points) (b) If an aliminium solid shaft was used instead of an aliminium hollow shaft, what will be the twist angle under same torque value. (Assume that the solid shaft has the same length and cross- sectional area with the hollow shaft.) (15 points) (c) Discuss by comparing the twist angle results of both shafts that is given to you in case (a) and you obtained in case (b). (15 points)