Determine the carburizing time necessary to achieve a carbon concentration of 0.30 wt% at a position 4 mm into an iron–carbon alloy that initially contains 0.10 wt% C. The surface concentration is to be maintained at 0.90 wt% C, and the treatment is to be conducted at 1100°C. Use the diffusion data for γ-Fe.

Ahouse has the following electrical appliance usage (1) single 40w lamp used for 4 hours per day (2) single 60w fan used for 12 hours per day (3) single 200w refrigerator that runs 24 hours per day with compressor run 12 hours and off 12 hours find the solar power inverter size in watt with correction factor of 1.25.

During a steady flow process, the change of energy with respect to time is zero. a)- true b)- false

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