BALLS BY THE RULES

eleven sports at true relative size — circumference, mass, pressure, and who sets them

Built as a memo rather than a table: the thing worth hanging it up for reads across the room, with the full reference in smaller type below it.

Three sizes in one archive — from a sheet on the fridge to a poster on the wall.

Formats: A4 · A3 · A2
What you get: Print-ready PDFs, one per size, with every letterform converted to outlines — nothing to install, nothing to shift.
Subject: sport · everyone · comparison · gym

Every row is taken from the current rules of the body named beside it. Diameters are computed from circumference as C/π, and densities from the same figures; where the rules give a range, its midpoint is used.

EVERY INFLATED BALL WEIGHS THE SAME PER UNIT OF VOLUME

Divide each ball’s mass by its own volume and it turns out that a football, a basketball, a rugby ball and even a table-tennis ball all land on roughly the same density, near eight hundredths of a gram per cubic centimetre. That is about one twelfth of water, and the reason is single: they are almost entirely air, and the casing weighs very little.

Which is why they all float equally well. Of the eleven balls on this sheet exactly one is denser than water: the golf ball, solid, at 1.13 g/cm³. The cricket ball, the heaviest of them in the hand, comes to 0.81 — it floats too.

On the sheet

Every row is taken from the current rules of the body named beside it. Diameters are computed from circumference as C/π, and densities from the same figures; where the rules give a range, its midpoint is used.
Colour carries meaning, but meaning never rests on colour alone — the sheet reads in black and white.
Nothing about how it was made: the sheet carries only what the reader needs.

Printing

Three sizes in the archive: A4 — 210×297 mm, A3 — 297×420 mm, A2 — 420×594 mm.
All text is converted to outlines. No fonts to install, and nothing shifts on another machine.
White background and sparing fills — it prints on a home printer without draining the cartridge.
Margins of at least 10 mm: a home printer cannot print to the edge.
No stroke thinner than 0.3 mm, so nothing disappears in print.

Why the numbers can be trusted. Every countable number here is computed from data rather than typed in, and the sheet must pass 5 independent checks before it is allowed to build — how many items there are, the order they come in, and the claim in the highlighted box itself. If one fails, there is no file.

BALLS BY THE RULES

EVERY INFLATED BALL WEIGHS THE SAME PER UNIT OF VOLUME

On the sheet

Printing

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