MEPX
Chapter 1 of 13All chapters
  1. 1What physics is
  2. 2Units and measurement
  3. 3Describing motion
  4. 4The laws of motion
  5. 5Forces
  6. 6Energy and work
  7. 7Momentum and collisions
  8. 8Waves
  9. 9Sound
  10. 10Light and optics
  11. 11Electricity and magnetism
  12. 12Heat and thermodynamics
  13. 13Modern physics

Chapter 1 of 13

What physics is

Models that predict, not stories that explain.

Prediction is the test

A physical law is a model that predicts what will happen and can be checked. Newton's laws are still taught because they predict everyday motion accurately, even though relativity replaced them at extremes.

  • Every model has a range where it works and a boundary where it fails.
  • Being wrong outside that range is expected, not a scandal.

Approximations on purpose

Physics ignores air resistance, friction and the size of objects when they do not matter. Knowing which simplification you have made is most of the skill.