You place your lunch leftovers in the refrigerator. Suppose the refrigerator nee

Question

You place your lunch leftovers in the refrigerator. Suppose the refrigerator needs to remove 2.2230E+4 J of thermal energy from your lunch to cool it to the temperature of the inside of the refrigerator. In the meantime, this means the refrigerator produces 2.8762E+4 J of thermal energy that it expels into the kitchen as a result.

The total work done by the compressor motor in the refrigerator is 6.532×103 J

The Coefficient of Performance for the refrigerator is 3.403

Your refrigerator actually acts like a heater in your kitchen. Suppose you have a small electric space heater that has a power output of 2.7kW. How long would this heater have to run to produce the same amount of heat as the refrigerator produced while cooling your leftovers? 1.065×101 s

Question: It takes electricity to run the motor on the refrigerator. If your cost of electricity is 16 cents per kilowatt*hour, how much does it cost (in cents - do not enter units) to cool your lunch down?

Explanation / Answer

Qc = 7.2 kJ
Qh = 9.7899 kJ

A.) W = Qh - Qc

B.) COP = Qc/W

C.) P = 1.9 kW
t = Qh / P

D.) Cost = (W*t)*$

Note: 1 kJ = 0.278 Wh = 0.278 * 10^-3 kwh

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