The mechanics chain mirrors how physics is taught: speed, distance and time (including the average-speed trap), then force and F = ma (with mass-vs-weight finally untangled), then energy — kinetic, potential and thermal, including why doubling speed quadruples braking distance and what a kilowatt-hour costs on your bill. The Ohm's law calculator covers the electrical family — voltage, current, resistance and power — with the water-pipe analogy that makes it click.

The matter-and-measurement tools: the unit converter (exact factors, the US-vs-imperial gallon trap, and the conversion failures that crashed a Mars probe), the temperature converter (the one conversion with a "+32" in it), the density calculator with its sink-or-float predictor and the Archimedes crown story, and the interactive periodic table — all 118 elements, read as a map rather than a list.

Constants and formulas follow standard SI definitions, worked examples use real numbers you can re-verify by hand, and the curious can go deeper in the blog — Newton's three laws is a good first stop.