I'm new to latex and trying to figure out the notation.
I'm trying to type out conversions, like (for example) 5 lbf * (4.4482 N / 1 lbf)= etc etc.
I'm not sure how to make the units show as units, or, at least, not as italics. I've seen how you can use \si{N}, but lbf isn't an SI unit, and I don't know how to combine \si with \frac.
Units are placed in upright font, and the spacing between a number and its unit is smaller than the usual spacing between words. Furthermore, the number and its unit should not be broken up over two lines of text.
This is a good article that discusses typesetting mathematics for science: http://www.tug.org/TUGboat/Articles/tb18-1/tb54becc.pdf
The following macro can be placed in the preamble to help with units. In works in and out of mathmode.
\providecommand*{\unit}[1]{\ensuremath{\mathrm{\,#1}}}
Here is my example:
\documentclass[12pt]{article}
\usepackage{amsmath}
\usepackage{amssymb}
\providecommand*{\unit}[1]{\ensuremath{\mathrm{,#1}}}
\begin{document}
You can type units in manually, $1,\mathrm{lbf} = 4.4482,\mathrm{N}$
Or you can use the macro defined above:
\begin{equation}
5.00\unit{lbf} \left(\frac{4.4482\unit{N} }{ 1\unit{lbf}}\right) = 22.2\unit{N}
\end{equation}
These give the same result:
22.2\unit{N}
22.2,N
$22.2,\mathrm{N}$
Since mathmode gets rid of whitespace, this doesn't look right:
$1,\mathrm{N} = 1,\mathrm{kg m/s^2}$
This looks right:
$1,\mathrm{N} = 1,\mathrm{kg,m/s^2}$
\end{document}
siunitxlets you declare new units, see e.g. https://tex.stackexchange.com/questions/27614/expressing-capital-m-for-molar-in-siunitx-package/27618#27618 Then if you've defined an\lbfunit, you can do e.g.\SI{4.4482}{\newton\per\lbf}. Note capital\SIwhich is for a number with a unit. – Torbjørn T. Feb 04 '19 at 20:19siunitxpackage allows you to define your own units and typesets them in a consistent way. – Bernard Feb 04 '19 at 20:20