What you'd probably say, and the word that gets you the right answer. Physics is unusually strict about these — several pairs that sound like synonyms in English mean genuinely different things here.
Physics splits by what's being studied, and the divisions are sharp. Naming the branch tells a helper which set of equations to reach for.
The working vocabulary, grouped by territory. Skim a group before you head into it; search once you're already lost in it.
Physics runs on abbreviations. Here's what each letter stands for and how the units are read aloud.