@johnmdudley
I actually wonder about that in a lot of English nouns, such as mathematics (vs arithmetic, geometry), or semantics, or hermeneutics. Or physics (in GER: Physik) vs music, for instance. Or how abt sports? (gymnastics vs football).
In GER, btw, it's Dynamik, i.e. clearly singular. Have a good night from here, John (this is perhaps my last post on this platform).