find the solidification time of the two iron castings when both are poured

(with no superheats) into the sand molds at initial temperature 28°c.

(i) a slab shaped casting of 10 cm thickness, (ii) a sphere of 10 cm in dia. iron: freezing temp: 1540°c; l= 272 kj/kg; density = 7850 kg/m3 sand: c = 1.17 kj/kg-k; k = 0.865 w/mk; density = 1600 kg/m3

Coiled springs ought to be very strong and stiff. si3n4 is a strong, stiff material. would you select this material for a spring? explain.

Apipe with an outside diameter of 15 cm is exposed to an ambient air and surrounding temperature of -20°c. the pipe has an outer surface temperature of 65°c and an emissivity of 0.85. if the rate of heat loss from the pipe surface is 0.95 kw per meter of length, the external convective heat transfer coefficient (h) is: (a) 12.5 w/m"k (b) 18.6 w/mk (c) 23.7 w/mk (d) 27.9 w/mk (e) 33.5 w/mk

Draw the engineering stress-strain curve for (a) bcc; (b) fcc metals and mark important points.