Originally Posted by
Siddy Hi,
I have a formula i have to use, depending on the data give in the exam i will have to re-arrange it before using it. Problem is i just cant get it work. I my notes i didnt use a lot of detail and i cant remember how i did it in the class, i thought it was so simple at the time, but now i just cant do it! My lecture says its too easy to need worked solutions, so all i have is the answers, not worked solutions.
f = c ( s - a ) / s ( c - a )
If the question ask for "f", obviously i can do it, but sometimes it asked for "s".
When i try to rearrange, i end up getting "s/s" at some point and the formula explodes in my face.
eg:
c= 0.98
a= 0.89
f= 0.45
s= ? (answer sheet says 0.928)
if you are interested the forumla is for calculating the fraction crystallinity in a polymer sample, from densities, its simple linear relationship.
Using this page to generate an image from LaTeX:
The LaTeX:
Code:
\\
f=\frac{c(s-a)}{s(c-a)}\\
\\
fs(c-a)=c(s-a)\\
\\
s(fc-fa)=cs-ca\\
\\
s(fc-fa-c)=-ca\\
\\
s=\frac{-ca}{fc-fa-c}