A 50 mm × 45 mm × 20 mm cell phone charger has a surface temperature of Ts = 33°C when plugged into an electrical wall outlet but not in use. The surface of the charger is of emissivity ε = 0.92 and is subject to a free convection heat transfer coeffcient of h = 4.5 W/m2 ⋅K. The room air and wall temperatures are T[infinity] = 22°C and Tsur = 20°C, respectively. If electricity costs C = $0.18/kW ⋅ h, determine the daily cost of leaving the charger plugged in when not in use.

The higher the astm grain size number, the finer the gran is. a)-true b)-false

Assuming compressible flow of air and that the measurements are done at flagstaff a pitot static tube that gives the difference of total and static pressure measures 0.35 m of mercury. what is the velocity of air? assume the temperature to be 300k. (submit your excel or matlab calculation sheet)

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?