Consider air in an truck tire maintained at a pressure of 220 kPa (gage). The atmospheric pressure is 94 kPa. The air in the tire is at a temperature of 25 oC. A 4 mm diameter hole develops in the tire wall, due to a puncture. Approximating the flow out of the hole as isentropic, determine the initial mass flow rate of air leaving the tire [kg/sec].

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