8.65 Consider a thin-walled, metallic tube of length L ϭ 1 m and inside diameter D i ϭ 3 mm. Water enters the tube at m ⅐ ϭ 0.015 kg/s and T m , i ϭ 97 Њ C. (a) What is the outlet temperature of the water if the tube surface temperature is maintained at 27 Њ C? (b) If a 0.5-mm-thick layer of insulation of k ϭ 0.05 W/m ⅐ K is applied to the tube and its outer surface is maintained at 27 Њ C, what is the outlet temperature of the water? (c) If the outer surface of the insulation is no longer maintained at 27 Њ C but is allowed to exchange heat by free convection with ambient air at 27 Њ C, what is the outlet temperature of the water? The free convection heat transfer coefficient is 5 W/m 2 ⅐ K.

Slip occurs via two partial dislocations because of (a) the shorter path of the partial dislocation lines; (b) the lower energy state through partial dislocations; (c) the charge balance.

Aquick transition of the operating speed of a shaft from its critical speed will whirl amplitude. (a) increase (b) limit (c) not affect (d) zero

A3-mm-thick panel of aluminum alloy (k 177 w/m-k, c 875 j/kg-k and ? = 2770 kg/m) is finished on both sides with an epoxy coating that must be cured at or above t,-150°c for at least 5 min. the production line for the curing operation involves two steps: (1) heating in a large oven with air at ts,0-175°c and a convection coefficient of h, 40 w/m2. k, and (2) cooling in a large chamber with air at 25°c and a con- vection coefficient of he 10 w/m2.k. the heating portion of the process is conducted over a time interval te which exceeds the ime required to reach 150°c by 5 min (h = r + 300 s). the coating has an emissivity of ? = 0.8, and the temperatures of the oven and chamber walls are 175 and 25°c, respectively. if the panel is placed in the oven at an initial temperature of 25°c and removed from the chamber at a safe-to-touch tempera ture of 37°c, what is the total elapsed time for the two-step curing operation?