About physics2u
A one-stop physics reference built to a single standard of rigour and honesty — for students who want it done properly, and for scientists who need one source they can cite.
About me
physics2u is written and maintained by FR — a physicist by training (B.Sc. (Hons.) in Physics, M.Sc. (PE)). The site grew out of a straightforward frustration: most physics explanations, in print and online, skip the assumptions, stay quiet about where a result stops being true, and gloss the one step that was actually hard.
So everything here is written to the standard I wanted as a student — every assumption declared with the cost of dropping it, every step justified, every result told exactly where it breaks, and a worked number so it lands at a real scale. Where a page falls short of that, it is mine to own and yours to report.
The derivations are authored independently and tiered from a plain-language reading to full rigour, so the same page serves a first-year student and a working scientist checking a factor.
What this is
Every result is worked from stated assumptions to a checked conclusion — no "it can be shown that". Coverage grows unit by unit, and the reference is expanded and deepened over time.
Scope: classical mechanics through the standard undergraduate core and beyond, with each derivation tiered from plain-language to full rigour.
Browse the curriculum →Authored independently
Derivations are written from first principles here, not copied or paraphrased from any textbook. Where a standard treatment exists, the source is named for comparison, never followed line-by-line.
Each derivation carries its own assumption ledger and units check, so you can audit the logic without trusting the author.
Report an error
Found a wrong sign, a dropped factor, a broken units check? Tell us the page and the line — corrections move through a fixed pipeline so nothing is quietly patched.
How it is built
Set in DM Sans for text, IBM Plex Mono for labels and code, and IBM Plex Serif for mathematics. Typography is chosen so equations read as equations, not as prose.
Static pages, no tracking, no paywall — static, fast, free. The whole site is plain files that load without JavaScript for reading.
Math is rendered as semantic HTML with serif italics rather than images, so it stays selectable, searchable, and legible at any zoom.