On a hot day, you are in a sealed, insulated room. The room contains a refrigera
ID: 2148229 • Letter: O
Question
On a hot day, you are in a sealed, insulated room. The room contains a refrigerator, operated by an electric motor. The motor does work at the rate of 248 W when it is running. Assume the motor is ideal (no friction or electrical resistance) and that the refrigerator operates on a reversible cycle. In an effort to cool the room, you turn on the refrigerator and open its door. Let the temperature in the room be 319 K when this process starts, and the temperature in the cold compartment of the refrigerator be 255 K. At what net rate is heat added to (+) or subtracted from (?) the room and all of its contents?____W
Explanation / Answer
Whatever heat is removed from the inside of the fridge is radiated into the room, so it would not make a usable air conditioner - unless you climbed into the frig and shut the door - but then you would soon run out of oxygen and suffocate. But the net would be an increase in room temperature. The 248 W used by the motor is converted to mechanical action, (pumping Freon), but then it's dissipated as heat along with the heat removed from inside the box.