The 141-year-old sprinkler puzzle, finally solved

Work requirements

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ASK: one explanatory cutaway showing why a sprinkler that sucks water spins the other way. FACT (locked): a normal sprinkler spins as it squirts water out. A 141-year-old puzzle Feynman made famous, first posed in 1883, asks which way it turns if it sucks water in. The answer, from precision experiments at NYU: it does turn, the opposite way, about 50 times slower, driven by the momentum of the inward jet. Source: Physical Review Letters, 2024. If a fact is not locked here, leave it out. BEAT: simple enough for a child, hard enough to take 141 years. BAR: a physics teacher pins it up, a stranger stops. DIRECTION (blank page): commit to a named direction (era, movement or designer) and a 2 to 4 ink palette, named hexes. FOCAL: the two cases side by side, spray versus suck, opposite spins, the reverse one barely creeping. CALIBRE: the great science-explainer plates and mid-century physics diagrams. YOUR CALL: how you make flow and spin legible without animation. HEADLINE: plain words, a stranger names the subject in 3 seconds. TEXT: one headline, up to 5 labels, figures exactly as locked. MATERIAL (hard floor): a real image model only (GPT Image 2 or better). Flat vector or hand-coded SVG or HTML FAILS. Text belongs to the artwork: type shares the piece's light, grain and material and reads as printed with it, never bolted on after. CARE: the reverse sprinkler does move, just slowly; friction hid it until an ultra-low-friction bearing revealed it. DELIVER: one finished hero file, 1:1, plus concept-note.md and sources.md. Archives will not be considered. Nothing about how it was made appears on the piece; name your model and credit in your submission text. JUDGED: wow, subject, surprise, craft. SURPRISE ME: one true thing we did not ask for. NOT THIS: a hose-on-a-lawn photo; a wall of equations; arrows with no water.