perfectly insulated room has temperature 72o. the source of climate control is turned off. But a refrigerator is put into the room and plugged in. The adjustment inside the refrigerator is turned to “maximum cold” and the door to the refrigerator affects the temperature in the room. After one hour, is the room hotter or colder than the original 72o.

Along wire of diameter 1 mm is submerged in an oil bath of temperature ∞ 31°c. the wire has an electrical resistance per unit length of 0.01 ω/m. if a current of 103 a flows through the wire and the convection coefficient is 500 w/m2·k, what is the steady-state temperature of the wire? from the time the current is applied, how long does it take for the wire to reach a temperature that is within 1°c of the steady-state value? the properties of the wire are 8000 kg/m3, 500 j/kg·k, and 20 w/m·k.