Physics you can see.

Small, honest experiments for concepts that are usually hidden inside numbers. Each page starts with one question, then lets you move the quantities yourself.

Featured

Three to start with

Fluid flow

Why the straw gives up

See why a long drink straw becomes impossible to sip through while a much longer garden hose stays effortless.

Motion

Throwing a potato into a hole

Set a release height, launch angle, and speed, and see whether a 200 g potato lands in a hole 3 m away — and how two very different arcs can land in the same spot.

Speed

Earth to the Moon, at real speed

Watch light cross the Earth–Moon gap, and magnify the tiny first part of the same journey for slower travellers.

Everyday maths

One page

Quantities from an ordinary day — a storm, a car, a bicycle, a bookshelf, a pizza order, a savings account — that you can check against your own life.

01 / Geometry

Why standing up lets you see farther

Earth curves away beneath you — raise your eye height and watch the visible horizon push out from a few kilometres to thousands.

Discoveries

Two pages

The equations that changed what we knew — each one reduced to the quantities you can move yourself.

13 / Speed

Earth to the Moon, at real speed

Watch light cross the Earth–Moon gap, and magnify the tiny first part of the same journey for slower travellers.

17 / Geometry

Two sticks measure a planet

Compare shadow angles at two cities a known distance apart, the way Eratosthenes sized up the Earth around 240 BC.

Fun physics

Two pages

Oddities and quantities too big to picture, taken seriously enough to actually compute.

30 / Fluid flow

Why the straw gives up

See why a long drink straw becomes impossible to sip through while a much longer garden hose stays effortless.

45 / Motion

Throwing a potato into a hole

Set a release height, launch angle, and speed, and see whether a 200 g potato lands in a hole 3 m away — and how two very different arcs can land in the same spot.

What's next

More equations, waiting their turn.

The next batch is all kitchen-table science — grab something from around the house, take a real measurement, and check it against the equation.

Everyday maths

Why the spoon feels colder than the table — both are room temperature, but touch metal and wood and your hand disagreese = √(kρc)idea
How deep is the well — drop a stone, count the seconds to the splash, and back out the depthd = ½gt²idea

Fun physics

Melting ice doesn't raise the glass — float an ice cube in a full glass, mark the waterline, and watch it not moveρ_iceV_ice = ρ_waterV_dispidea

Every visual is self-contained, approximate only where stated, and designed to be played with. Each page is a single HTML file with no build step and no external dependencies — open one directly in a browser and it works.