**General comments**

I thought the lecture went pretty well. In class experiments/demos
are always fun. We will do another one on Monday. It is clear from the PRS responses
that there is confusion regarding the various forms of the First Law of Thermodynamics.
This is natural, I have introduced a lot of new terms, etc. However, since it
is a common point of confusion, **be careful when you do the homework to use
the appropriate form of the equation for the job at hand.**

** I left my PRS clicker @ home. Does that mean that
I wasn't in class today according to your records?** (1 student)
Yes it does. If you tell me who you are I can correct the records to reflect
your attendance.

** Note about the TA session yesterday. It had the
potential to be a lot more useful than it was. If we were told about it beforehand,
we could have prepared questions to ask.** (1 student). You are
right. For the record, U5 and U6 are titled "The Language of Engineering"
and will cover a lot of the basics that are relevant for all of the disciplines
as well as items identified in the web-based diagnostic as most in need of remediation.
U7 will be a mid-term feedback and discussion session, and U8 will be an end-of-term
feedback and discussion session.

** There was no lecture, just one example**
(1 student). I will assume this is a criticism and not a plaudit. I will note
that by my watch, we spent 5 minutes on the example itself and 12 minutes on
thinking about what information we need. Prior to that we did 3 PRS questions,
discussed the applicability of the various equations, described enthalpy, reviewed
the necessity for knowing a quantity like specific heat, etc.

**Responses to 'Muddiest Part of the Lecture Cards'**

(60 respondents)

1) * Unclear on all the various versions of the First
Law, when they are applicable, etc.* (18 students) I have started
to put together a list of all the First Law equations and the associated assumptions.
When I complete it, I will put it up on the web.

2) * We didn't derive the du=cvdT and dh=cpdT equations*
(1 student). Right. And I don't intend to derive these in class. I expect you
to work through these on your own. If you have questions on the derivations
that are presented in the notes, please
let me know. I will however, spend some more time on talking about the uses
of these equations, limitations, etc.

3)* I am not sure what you mean
by quasi-static* (1 student). Read this
again. Here is an alternative explanation from Prof. Greitzer's class notes
for 16.050:

4) * Enthalpy.I
don't quite see how enthalpy is applicable yet* (4 students).
For now take it as just another property of the system that I would like you
to begin to get more comfortable with, think about its physical meaning, and
if you desire, read ahead to see how
we will use it with the Steady Flow Energy Equation.

5) * The calculation for the last experiment was
unclear to me* (9 students). Here is a write-up
of my estimation procedure.

6) * Cv, Cp ----> ? :)*
(10 students) First, read the section of
the notes again to familiarize yourself. Here are the most important points:
1) cv and cp tell us how many Joules of heat transfer are required to change
the temperature of a material by 1 Kelvin via a constant volume or constant
pressure process, respectively. 2) These are properties of the material we are
dealing with (that is they are different for different gases, solids, etc.).
3) In general, u is a function of two properties of the system (as is h), however,
if u=u(T) only and h=h(T) only then du=cvdT and dh=cpdT. If this gas also obeys
pv=RT (a thermally perfect gas), then the gas is called an

7) * No mud, fun example, etc.* (17 students).