1) Explain the differences between fail safe design and safe life design concepts. [2 marks] 2) What is the shape of the contact area between two cylinders with axes crossed at a right angle (in space) if they have the same diameters and if the diameters are different? [2 marks] 3) Write three factors which influence the S-N fatigue curve and explain how they influence the life of mechanical parts. [3 marks] 4) Briefly explain the two types of abrasive wear. [2 marks] 5) What are the main assumptions made in the derivation of Reynolds' equation? [2 marks] 6) Journal bearings are preferred to rolling elements bearings at the support of the crank shaft of internal combustion engines. Explain the reasons for this choice. [3 marks] 7) State the law of conjugate gear - tooth action. [2 marks] 8) What are the potential modes of failure of coil springs? [2 marks] 9) Discuss advantages and disadvantages of flat belt transmission in comparison to other types of mechanical transmissions. [2 marks]