Day 7 Entropy

First we discussed entropy. Entropy is DS = Q/T. One example we went over was water and the phase changes.

White board explanation of fusion and how the arrangement of water molecules related to the entropy. Steam has higher disorder then Ice.

Then we choose three examples of cases where entropy increases. We didnt take a picutre of the white board but three examples would be: The phase changes of water, burning paper, and opening of a soda.

We did draw an Entropy Diagram. T verses entropy (S).

Isothermal cases or horizontal. Isoenthropic are vertical.

We then moved onto the Stirling Cycle. We are missing the demonstration Prof.Mason provided. Prof. Mason showed that the Stirling demonstration worked by melting ice on top of the boiling water started the fan.

We then did Active physics problems related to the Stirling Cycle.

Picture of the Stirling cycle efficiency. 26.8%

We then found COP, Coefficient of Performance. We also found the BTU. One BTU is about 1054J.

White board work. COP is 3500W. We also found the BTU = 1054J.

 We then found the operating time.

White board work. The time ended up being 14 minutes.

Summary:
Discussed entropy. Defined it as DS = Q/T. Entropy only depends on T.
Found the effienecy of a Stirling Engine, turns out to be 26.8%.
We talked about the ridiculousness of BTU and found it to be 1054J. Learned about COP and how much time is needed to operate a air conditioner.