# Common Mistakes



## navyasw02 (Oct 3, 2010)

With under a month to go, what are your most common mistakes made in problems?

Mine is forgetting to put everything in inches into feet, particularly when it comes to diameters given in inches.


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## tmacier (Oct 3, 2010)

navyasw02 said:


> With under a month to go, what are your most common mistakes made in problems?
> Mine is forgetting to put everything in inches into feet, particularly when it comes to diameters given in inches.


I have found that I need to slow down and read the problem -


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## IlPadrino (Oct 3, 2010)

navyasw02 said:


> Mine is forgetting to put everything in inches into feet, particularly when it comes to diameters given in inches.


It's been said that if you don't make any mistakes with units, you'll pass - regardless of your preparation!


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## HokieGirl (Oct 4, 2010)

Units, units, units. And, being careful when you enter things into your calculator. I ended up with extra time in the morning session and I went back and just double checked some of my equations. I had entered one into my calculator wrong. It was a classic error for me. The equation I wrote down had pi/2 and I entered pi/4 into my calculator since I was so used to using pi/4 when calculating the area of a circle. It is so easy to feel rushed during the exam and wanting to finish each problem as quickly as possible to give yourself more time later. But, spending an extra 30 seconds to a minute is worth it on the problems you have to calculate an answer for.


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## snickerd3 (Oct 4, 2010)

units units units

also make sure you reread the problem statement to see what units they want the answer it...more likely than not it will be different than what the info in the question is.


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## IL-SE (Oct 4, 2010)

Read each problem twice and underline exactly what you are solving for. It's easy to skim over what the problem is actually asking for.

More than once I solved a problem that I thought asked "which of the following is..." only to find that more than one answer worked and that it was actually asking "which of the following is NOT..."


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## Sschell (Oct 4, 2010)

pay attention to details... esp. units.

Read all possible answers.

If you can't figure one out, eliminate as many wrong answers as you can before you guess.


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## oluade PE (Oct 4, 2010)

sschell_PE said:


> pay attention to details... esp. units.
> 
> Read all possible answers.
> 
> ...


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## Lily (Oct 5, 2010)

My commun mistakes, especially when I am sleepy :wacko:

1) Using diameter instead of radius (pressure vessels problems for example)

2) Not typing the right formula in the calculator

3) Unit conversion, specially when gc is involved ( I am more used to SI units than US units)

4) Forgetting factors like safety factors and efficiencies


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## Sschell (Oct 5, 2010)

Be careful what you eat for lunch.


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## NerdHerd (Oct 6, 2010)

sschell_PE said:


> Be careful what you eat for lunch.


My common mistake has been solving for the wrong thing. For example, when given the working pressures and temperatures of an adiabatic turbine in a rankine cycle, the problem would ask for the efficiency of the cycle, and I would solve for the efficiency of the turbine. And the efficiency of the turbine is of course a choice for one of the answers.


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## Sschell (Oct 6, 2010)

NerdHerd said:


> sschell_PE said:
> 
> 
> > Be careful what you eat for lunch.
> ...


Exactly what I meant. For example, when I have the carne asada burrito off the roach coach, it throws my working pressures and temperatures out of whack... this can cause vent to atmosphere events (or worse), and subsequent loss of efficiency.


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