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.

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

B) What is the Coefficient of Performance for the refrigerator?

C) 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?

D) 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

For part A, you take the final gas amount minus the initial (keep in mind that they told you that the liquid at the beginning was 54% NOT the gas!). Take this to get heat absorbed (49% * 7g * Lv).
For B, it's a trick (sort of), the answer is delta U, which is the number they gave you in this part!

For part C, you take A + B, which should be 634500 J if I did my math right!

I just finished a similar problem, so I hope this helps you!

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