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Q6. An intermediate propulsion shaft is fitted to an engine of power 8 MW operating at 120 rev/min. The shaft is solid, with a coupling flange at each end. On each flange there are 12 bolts, with a pitch circle diameter of 1. 75 times the shaft diameter. The limiting torsional shear stress for the shaft material is 160 MN/m² and the limiting shear stress for the bolt material is 180 MN/m².

Calculate EACH of the following:

(a) the diameter of the shaft if a safety coefficient of two is required for the shaft material. (8)

(b) the diameter of the bolts if a safety coefficient of three is required for the bolt material. (8)