Section A
Q1.
(a) A V-belt of 6. 5 cm2 cross-section has a groove angle of 30° and an angle of lap of 160° with coefficient of friction (mu) = 0. The mass of the rope is 1. 5 kg/m. The maximum safe stress is 850 N/cm^2. Calculate the power that can be transmitted at 25 m/s.
(b) A flywheel is mounted on a vertical shaft as shown in the figure. The ends of the shaft are being fixed. The shaft is 50 mm in diameter, the length l1 is 900 mm and l2 is 600 mm. The weight of the flywheel is 0.5 ton and its radius of gyration is 500 mm. Calculate the natural frequency of the longitudinal vibration of the system. Take Young's modulus (E) = 210 GPa.
(c)
A steel rod 5 m long and 20 mm in diameter is subjected to an axial pull of 50 kN. Determine the change in volume of the rod. Take Young's modulus (E) = 210 GPa and Poisson's ratio ($
u$) = 0.
(d) What are the difficulties in hardening low carbon steel through heat treatment ? How can surface hardness be imparted through carburizing, nitriding and cyanide hardening ?
(e) What is the difference between an alloy and a composite ? Explain with the help of suitable examples. Also, cite the differences in strengthening mechanism for large particle and dispersion-strengthened composites.