Learn physics by watching things fall
A hands-on course that starts with a rolling cart and ends at the edge of the quantum world: every lesson pairs readable theory with an interactive lab you can launch, tilt, collide and tune — then a short quiz locks it in. Halfway through, you measure the Earth's gravity with a shoelace and a phone.
Motion
0/3Before asking why things move, learn to say precisely how: position, velocity, acceleration — and the graphs that turn motion into something you can read.
Position & Velocity: Saying Where, Precisely
Physics starts by replacing 'it moved' with numbers — and the graph of those numbers already answers questions your eyes can't.
Acceleration: When Velocity Itself Changes
The hardest idea in kinematics is that speeding up, slowing down and turning are all the same thing — and that falling is its purest example.
Projectiles: Two Motions That Ignore Each Other
A thrown ball is two easy problems wearing a trench coat: steady sideways motion, plus plain free fall. Split them and everything computes.
Forces
0/3Why motion changes: three laws that run everything from a shopping trolley to the Moon — plus friction, the force that spends its life pretending motion is hard.
Newton's Three Laws: The Operating System
Motion doesn't need a cause — changes in motion do. Three sentences from 1687 that still run every machine, sport and orbit.
Friction: The Force That Hides in Plain Sight
It ruins ideal physics problems and makes walking possible. Two rules govern it — and one everyday surprise about what it does not depend on.
Gravity & Orbits: Falling Forever
The apple and the Moon obey one law. An orbit is not an escape from gravity — it is falling, aimed well enough to keep missing.
Energy & Momentum
0/2Two quantities the universe refuses to lose. Once you can track them, problems that look impossible become bookkeeping.
Energy: The Quantity That Only Changes Costume
Physics' best accounting trick: a number you can compute before and after any process — and it always balances.
Momentum: What Collisions Conserve
Mass times velocity survives every crash, explosion and rebound — which is why airbags work and why recoil is not optional.
The Backyard Capstone
0/1Three units of mechanics, cashed in: measure the Earth's gravitational acceleration with a shoelace, a weight and a phone — to within a percent or two.
Progress & backup
this browser onlyProgress lives in this browser; sync keeps a server copy reachable only by your code, and exports are plain files you own. Imports and links always merge — nothing is overwritten.