Polymers

[starquest]

I'm having a hard time comprehending polymers for the MD exam;  the degree of polymerization, mers, etc.   If it is a plug and chug problem, similar to the one in the 6MS book..I'm ok, but I am clueless on most of the others.   It just isn't sinking in. 

Does anyone have a link to a good study guide or something on the net...something that would provide more clarification than the few paragraphs in the MERM?   I started searching but haven't found the right source yet. 

I don't want to waste too much time on this topic but it concerns me being that it is in my depth area.  

 

[starquest]

I guess I should clarify with a problem that I'm stumped on:

How much HCL should be used as an initiator in PVC if the efficiency is 20% and the average MW of 7000 g/mol is desired?

Solution jumps right to 5 mol HCL/mol PVC based on the mer for 20% efficiency.....how was this obtained?    Mer consisting of 5 atoms (two carbons, 3 hydrogens) to one atom of Cl?  

The answer is '(5 mol HCL/mol PVC) * Avogadros # / 7000 g/mol'

 

[JHW 3d]

I'll go out on a limb and say that I can't see you having more than one of these questions (if that). With 3 weeks to go, blow this off. These aren't that hard but not worth the effort right now to figure it out.

I don't know where you're feeling deficient but I'd divert back to more prominent topics in your depth.

Or swing back and take a day to cover some of those gimme-the-points type questions in TFS -- like power cycles, refrigeration cycles, calculating a Darcy friction factor, etc. Don't dwell on these but getting a slam dunk answer correct quickly can be just as important as the multi-step depth problem. I hope you at least covered these a little... Someone else posted and seemed to indicate they didn't study TFS at all since it wasn't in their depth. With that approach you miss out and end up guessing on effectively easy answers which puts more pressure on acing problems from your depth.

 

[starquest]

You are probably right, it just bothers me that I can't grasp this topic.   I looked at it again over lunch, it is starting to sit in.   I guess I just can't grasp that single problem stated above.  I'm ok with the examples in the actual MERM and the problem in the 6MS book.  

I think I have a decent base on TFS/HVAC, I spent 62 out of 180 hours on these areas to date (not including working the 2011 ncees breadth problems)...thanks to those grueling MERM practice problems.  Focus is pretty much 90% depth from here on out. 

Regards,

Kevin

 

[JHW 3d]

Glad to hear it.

What about engineering Economics? Easy money.

 

[JHW 3d]

You have the Lindberg unit conversion book? Can't recommend that enough.

 

[starquest]

Yep, I rented it from Amazon...but found that I love it.  It will be a beneficial book to have post exam.    Have to look up how much it will cost me if I don't return it by May.  

There are a three or four econ problems in the 6MS book that I know well, plus the problems on the ncees practice exam.   I still plan on running thru the econ merm problems if I have time. 

I need to devote some time 're-learning' vibrations.   Vibrations used to be my primary competency when I was working on my grad degree in 2002-2004...now it's like reading Greek, WTH?

Kevin

 

[Phenomenon083]

What about engineering Economics? Easy money.

NCEES practice exams asking just to find EUAC and a simple problem about depreciation. But MERM covers a lot of topics and goes deep. Should I go with MERM or just cover the basic problems.

 

[JHW 3d]

Good question. Depends on how much time you have. It's late so you might just cover the basics if you haven't already. At a minimum you should feel very comfortable with the rate tables. The chapter is long (40-45 pp) but it's not too bad.

Personally I read the whole chapter I did about 80% of the PP. granted I put more emphasis on this and covered it earlier in my prep. As I've already said, my personal opinion is that these problems can and should be solved fast and accurately in order to collect the points and move on to actual hard problems. To me that was worth a day studying Econ.

I didn't want to be guessing or spending tons of time reading up how to solve these problems.

 

[starquest]

I found this link helpful for econ:

http://www.peexamquestions.com/category/basic-engineering/economic-analysis/

Note there is other good info in there for test prep.  The heat transfer section was helpful.    I also worked thru the 'FE Sample Exam'.  Only takes a few hours to do, but their problems and solutions are littered with errors!   It was frustrating but the errors were obvious.   I started working on their HVAC problems too but also ran into errors/typos, I quit at that point and went to the MERM problems. 

 

[Phenomenon083]

Good question. Depends on how much time you have. It's late so you might just cover the basics if you haven't already. At a minimum you should feel very comfortable with the rate tables. The chapter is long (40-45 pp) but it's not too bad.

Thank you for the reply and you are right. I am very comfortable with the rate tables, tax rate, depreciation stuff. So far the problems I have encountered on economics other than MERM didn't deviate problems from these areas. I went through most of the problems on MERM and PP on early stage of my preparation but haven't been working on those problems after that and I am afraid that without practice I have forgotten most of the uncommon problems on economics section.

 

[JHW 3d]

Another "book" I used with surprising frequency on the exam was a printed and bound copy of MERM index.