Physics 5 — Modern Physics
E = mc² and half-life
continues from lesson 4 — values defined earlier in the course stay live here
ELI5: mass is frozen energy at a staggering exchange rate, c². Convert a single gram completely and you get a power-plant's worth of energy.
= ~9×10¹³ J — a city's daily electricity, from a paperclip
Unstable nuclei cash that energy out at random, but statistically on schedule: half are gone every half-life. Carbon-14 (t½ = 5730 y) turns every old bone and timber into a clock.
C-14 remaining (%) vs age (years) — measure the fraction, read off the age
✓ pass one half-life, half remains — by definition
Real-world hook: E = mc² powers the Sun, nuclear reactors, and PET scans; half-life dating fixes the age of fossils, the Shroud, and the Earth itself. That closes the Physics track — motion, momentum, fields, heat, and the modern rules beneath them all.