{"product_id":"drinking-bird-thermodynamic-heat-engine-feynmans-favourite-toy","title":"Drinking Bird — Thermodynamic Heat Engine (Feynman's Favourite Toy)","description":"\u003cp\u003e\u003cstrong\u003eDips its beak in water. Forever. Not perpetual motion — a real heat engine running on evaporation.\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eRichard Feynman considered this one of the most instructive physical demonstrations in existence. It is not a perpetual motion machine. It is a genuine thermodynamic engine, driven by the temperature differential between the wet head (cooled by evaporation) and the warmer body. Evaporation cools the head, lowering the vapour pressure inside, drawing fluid up the neck, shifting the centre of mass, causing the dip. The dip wets the head. The cycle repeats indefinitely as long as there is water and a temperature gradient.\u003c\/p\u003e\u003cp\u003eEvaporative cooling, vapour pressure, centre-of-mass mechanics, and the second law — in one glass toy.\u003c\/p\u003e\u003cdiv style=\"margin:2rem 0;padding:1.5rem;background:#111;border:1px solid #d4af37;border-radius:8px;\"\u003e\n\u003ch3 style=\"color:#d4af37;margin:0 0 1rem 0;font-size:1.1rem;\"\u003e▶ See It In Action\u003c\/h3\u003e\n\u003cdiv style=\"position:relative;padding-bottom:56.25%;height:0;overflow:hidden;\"\u003e\u003ciframe style=\"position:absolute;top:0;left:0;width:100%;height:100%;border:0;\" src=\"https:\/\/www.youtube.com\/embed\/DOTt3vkg8vk\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture\" allowfullscreen\u003e\u003c\/iframe\u003e\u003c\/div\u003e\n\u003c\/div\u003e\u003cp\u003e\u003cstrong\u003eIncludes:\u003c\/strong\u003e Glass drinking bird · Felt hat · Weighted base · Feynman's analysis card\u003c\/p\u003e\u003cp\u003eAges 8+. Ships within 7–14 business days.\u003c\/p\u003e","brand":"Golden Physics Project","offers":[{"title":"Default Title","offer_id":54805544698148,"sku":"GPP-DRINKING-BIRD","price":16.99,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/1007\/2879\/9524\/files\/960px-Sipping_Bird.jpg?v=1781381706","url":"https:\/\/shop.goldenphysics.org\/products\/drinking-bird-thermodynamic-heat-engine-feynmans-favourite-toy","provider":"Golden Physics Project","version":"1.0","type":"link"}