Relativity, frames and mass–energy

What this note covers

1. Identify inertial frames and invariant light speed
2. Calculate the Lorentz factor without losing its meaning
3. Choose proper time using the events
4. Length contraction concerns simultaneous endpoint positions
5. Relativistic energy and mass–energy equivalence
6. Connect relativity to measurements and limits
7. Relativistic momentum and the speed limit
8. Worked light-clock journey: identify which time is proper

8 sections · 10 key terms & formulas · 6 common mistakes