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.

What is the total work done by the compressor motor in the refrigerator? (Ignore any thermal loses due to friction in the motor.)

6.532×103 J

What is the Coefficient of Performance for the refrigerator?
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

This is what I need the answer to

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

We need to convert the work done in Joules to kwhr

1 Joule = 2.78 X 10^-7 kwhr

You have 6532 Joules, and that converts to 1.816 X 10^-3 kwhr

Now, multiply that by 16 cents per kwhr

1.816 X 10^-3(16) = .029 cents (much less than a penny)

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