Wanting to write units properly

Question

Could anyone explain how I write units properly in LaTeX? In the form kg.s^-1. They come out all slanted and squished together when i use math mode and \frac.

Answer 1

The siunitx package will interpret the units correctly

\documentclass{article}
\usepackage{siunitx}
\begin{document}
\noindent%
\si{kg.s^{-1}}\\
\si{\kilogram\per\second} \\
\si[per-mode=symbol]
{\kilogram\per\second}
\end{document}