THE ELECTROMAGNETIC SPECTRUM
eighteen decades of frequency · and how much of it the eye sees
PLASTIC RESIN CODES
the seven codes on the bottom of an article per ASTM D7611: which resin each number names and what it means for sorting
RESISTOR COLOUR CODE
the bands, the tolerances and the preferred series of two standards
ROCK CLASSIFICATION
the three classes, 24 named rocks and the cycle that links them — after USGS and NPS
THE SAFFIR-SIMPSON SCALE
five categories of hurricane wind — and how much more damage each next one does
SPECTRAL LINES
five gases on one wavelength scale, from the violet edge to the red
SPEED THRESHOLDS
six thresholds where a different physics begins · every figure computed, not typed
WHAT A TORNADO BREAKS
twenty-eight damage indicators — and the wind at which each one gives way
TORQUE
why the same dumbbell grows heavier as the arm rises, and how to work it out in advance
ANIMALS
the main branches — from comb jellies to chordates · who is actually related to whom
THE TREE OF LIFE
who sits inside whom · where animals, fungi and plants actually are
VERTEBRATES
from lamprey to bird · and why "fish" and "reptiles" are not groups