What's that g_c Factor?

I've posted this quesiton in the physics category but haven't got a good answer so far.





I'm studying in a Petroleum Production Technology manual. The author is trying to deduce a formula describing the flow of petroleum (oil and gas) from the reservoir through the tubing string to the surface. He used the conservation of energy principle and kept dividing the mass by a dimentionless factor (g_c).


For example: the kinetic energy becomes: m.v2/(2g_c)


and the potential enegy becomes: mgh/g_c.


Can anybody guess what this g_c is? It's basically "g" with a "c" subscript.


Let me write the complete equation as it appeared in the book:


U1+p1V1+mv1 square / 2g_c+ mgh1/g_c + Q -Ws = U2 +p2V2+ mv2 square /2g_c +mgh2/g_c


Where:


U: internal energy


V: fluid volume


h: elevation


Q: heat added or removed


m: mass of fluid


v: fluid velocity


p: pressure


Ws: work done or supplied

What's that g_c Factor?
g_c is the gravitational correction factor for converting masses in terms of weight units (e.g. lbm) to mass units. When dealing with masses in pounds, then g_c is 32.17 ft/s^2/slug. If dealing with masses in slugs or grams, the g_c is 1.0 acceleration units/mass units.
Reply:Young guy: You are incorrect in your comment in the "Asker's Rating." Check out the following link to the "pound-force" entry on Wikipedia:





http://en.wikipedia.org/wiki/P... Report It