A thin-walled tube with closed ends has an inner diameter of 40 mm and a wall thickness of 2.5 mm. It contains a pressure of 10 MPa and is subjected to a torque of 3000 N·m. (a) What is the safety factor against yielding if the material is ASTM A514 (T1) structural steel? (b) Is the design adequate? If not, suggest a new choice of material.