\documentclass[draft]{article}
\usepackage[textwidth=4.5cm]{geometry}
\usepackage{blindtext}
\parindent=0pt
\begin{document}
interwordspace: \the\fontdimen2\font \    interwordstretch: \the\fontdimen3\font \    emergencystretch: \the\emergencystretch\par
\blindtext

\newpage
\begin{sloppypar}
interwordspace: \the\fontdimen2\font \    interwordstretch: \the\fontdimen3\font \    emergencystretch: \the\emergencystretch\par
\blindtext
\end{sloppypar}

\end{document}
