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Unit Conversion


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#1 jindalo

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Posted 22 June 2011 - 02:46 AM

Dear viewers,

I want the following units to be converted in the ways mentioned :

Units to be converted Units to which it is to be converted to

1 N/m2 kg/m s

1 J/kmol/K W s/ kg 0C

1 J/s/m/K W/m 0C

1 N/m kg/m

where,

N = newton
m = meter
s = second
J = Joule
kmol = kilomole
W = watt
kg = kilogram

I am in a very urgent need of these conversions.

Please help me................

#2 MrShorty

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Posted 22 June 2011 - 11:18 AM

On this site, we tend not to just give out answers. Learning how to convert from one complex unit to another is an important and useful skill for a student to develop. We love to help in developing these skills, but you won't learn the skill if you don't put some effort into it. Is there a specific step in these conversions where you are stuck?

A couple of hints (that you should already know) to help you get started, if you are stuck not knowing where to begin:

1) 1 W = 1 J/s (should help with the 2nd and 3rd)
2) dT of 1K is the same as a dT of 1 C.

If you can show us what you've done so far and what problem you are having, we'll be happy to help.

#3 kkala

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Posted 25 June 2011 - 11:30 AM

Agreeing with MrShorty, following additional notes can be of help.
1. In different systems of units, you can do the conversions yourself, if you know few basic conversions by heart. For instance, to convert 1 lb/ft3 to metric system for density, we recall that 1 lb=0.45359 kg (see Perry, but it had better be known by heart) and 1 ft=12 in=12x2.54 cm=30.48 cm=0.3048 m. So 1 lb/ft3 = 0.45359/0.3048^3 = 16.0184 kg/m3. Perry quotes 16.01846 kg/m3 for 1 lb/ft3 in the conversion factors.
Now that pocket calculators are so common, I find above procedure easier than going to conversion tables. Some calculators incorporate unit conversions in their buttons, e.g. HP 9s can directly convert in to cm, lb to kg, oF to oC, etc, by pushing the proper button. Physical meaning is also kept, minimizing risk for arithmetic error.
2. In same system of units, there can be different units of same quantity to be converted, e.g. Pa and Bar for pressure. Task is easier by knowing the basic components (dimensions) of each unit.
For instance, we want to convert Bar to Pa (pressure). In this case 1 Bar = 10^5 Pa by definition (in my opinion), so no conversion calculations are needed.

Note: Of course 1 Pa = 1 N/m2 (basic units) and 1 Bar = 10^5 Pa = 10^5 N / m2 = 10^5 N / 100^2 cm2 = 10 N /cm2. We had better know by heart that 10 N ~ 1 kgf, so 1 Bar ~ 1 kgf/cm2, indicating that 1 Bar was defined such as to be close to atmospheric pressure.
3. As an example let us consider the first conversion, N/m2. Force is mass x acceleration, so 1 N = 1 kg x m/s^2. Thus 1 N/m2 = 1 kgm/s^2/m^2 = 1 kg/m/s^2 (not kg/m s).
4. To the useful hints of the post by MrShorty, add the note that kg in last conversion (N/m to kg/m) must be kgf (kg of force ~ 10 N), not mass kg.
Hopefully above helps in general, there are a lot of mistakes in unit conversions, even considered as simple things.

Edited by kkala, 25 June 2011 - 11:34 AM.


#4 ELEMAN

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Posted 25 June 2011 - 12:50 PM

Hello everybody:

jindalo, in addition to the comments of MrShorty and kkala, the information of this thread can be of some help for you: the Conversion Railroad of Art Montemayor and the Uconeer conversion software of Harvey Katmar. http://www.cheresour...h__1#entry11210

Good luck!

#5 Madhan Kumar

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Posted 28 June 2011 - 02:42 AM

Hi,

I collected from net resources. May be useful for you.


Cheer's
MK_Chem

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