Indian Institute of Technology Madras (IIT-M) 2003 M.Tech Mechanical Engineering mechanical engg-gate - Question Paper

19. A diesel engine is usually more efficient than a spark ignition engine because
(a) diesel being a heavier hydrocarbon, releases more heat per kg than gasoline
(b) the air standard efficiency of diesel cycle is higher than the Otto cycle, at a fixed
compression ratio
(c) the compression ratio of a diesel engine is higher than that of an SI engine (d) self ignition
temperature of diesel is higher than that of gasoline
20. In a Rankine cycle, regeneration outcomes in higher efficiency because
(a) pressure inside the boiler increases
(b) heat is added before steam enters the low pressure turbine
(c) avg. temperature of heat addition in the boiler increases
(d) total work delivered by the turbine increases
21. Considering the variation of static pressure and absolute velocity in an impulse
stream turbine, across 1 row of moving blades
(a) both pressure and velocity reduce
(b) pressure reduces but velocity increases
(c) pressure remains constant, while velocity increases
(d) pressure remains constant, while velocity reduces
22. During heat treatment of steel, the hardness of different structures in increasing order is
(a) martensite, fine pearlite, coarse pearlite, spherodite
(b) fine pearlite, coarse pearlite, spherodite, martensite
(c) martensite, coarse pearlite, fine pearlite, spherodite
(d) spherodite, coarse pearlite, fine pearlite, martensite
23. Hardness of green sand mould increases with
(a) increase in moisture content beyond six percent
(b) increase in permeability
(c) reduce in permeability
(d) increase in both moisture content and permeability
24. In Oxyacetylene gas welding, temperature at the inner cone of the flame is around
(a) 3500°C
(b) 3200°C
(c) 2900°C
(d) 2550°C
25. Cold working of steel is described as working
(a) at its re-crystallization temperature
(b) above its re-crystallization temperature
(c) beneath its re-crystallization temperature

(d) at 2 thirds of the melting temperature of the metal
26. Quality screw threads are produced by

Earning:   Approval pending.