What is Physics?
What physics studies, why models matter, and how measurement connects real systems to equations.
Foundations & Tools · Topic
Units, Dimensions & Measurement
The language of physics: how quantities are defined, measured, and combined. Build strong habits with units, dimensional analysis, uncertainty, and significant figures.
← Back to Foundations & ToolsPhysical Quantities & SI Units
Base quantities, SI base units, prefixes, and how to write units cleanly and consistently.
Derived Units
Build units like N, J, W, Pa from base units, and learn what the unit structure tells you physically.
Dimensional Analysis
Use dimensions to sanity-check equations, derive relationships, and catch mistakes before you calculate.
Precision, Accuracy & Uncertainty
Understand measurement quality, random vs systematic error, and how uncertainty should appear in results.
Significant Figures
Learn the sig-fig rules that keep your answers honest, including rounding in multi-step calculations.