{"product_id":"paddlewheel-joule","title":"Paddlewheel – Joule and the Mechanical Equivalent of Heat \/ 772 ft·lbf\/BTU Physics Sticker","description":"\u003cp\u003ePaddlewheel, a bearded brewer-scientist, works ropes on pulleys over a glowing copper vessel.\u003c\/p\u003e\u003ch3\u003eThe Physics\u003c\/h3\u003e\u003cp\u003eJames Prescott Joule let weights fall on pulleys, turning a paddle wheel inside an insulated vessel of water. Friction of the paddles warmed the water a tiny amount. Dividing the work done by the falling weights by the heat produced, he reported in 1850 (“On the Mechanical Equivalent of Heat”, Phil. Trans. R. Soc. 140, 61) that 772 foot-pounds of work raise one pound of water by 1 °F.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eW = J Q\u003c\/strong\u003e\u003c\/p\u003e\u003cul\u003e\n\u003cli\u003eW: mechanical work (ft·lbf)\u003c\/li\u003e\n\u003cli\u003eJ: mechanical equivalent of heat (ft·lbf per BTU)\u003c\/li\u003e\n\u003cli\u003eQ: heat produced (BTU)\u003c\/li\u003e\n\u003c\/ul\u003e\u003cp\u003eHeat and work are two forms of one thing, energy: the first law of thermodynamics. The SI unit of energy, the joule, is named for him.\u003c\/p\u003e\u003cp\u003e\u003cem\u003eHonest caveat:\u003c\/em\u003e The modern value is about 778 ft·lbf\/BTU (4.186 J per calorie), so Joule was within one percent.\u003c\/p\u003e\u003ch3\u003eOn the sticker\u003c\/h3\u003e\u003cp\u003ePaddlewheel hauls on ropes over pulleys, above a glowing copper vessel. Printed text: \u003cstrong\u003ePADDLEWHEEL\u003c\/strong\u003e with the line \u003cstrong\u003e772 ft·lbf\/BTU\u003c\/strong\u003e. Pixel-art kiss-cut vinyl sticker, white, in 2″, 3″, 4″ and 6″ sizes.\u003c\/p\u003e","brand":"Printify","offers":[{"title":"2\" × 2\" \/ White","offer_id":50964068532327,"sku":"33858343382434268743","price":4.99,"currency_code":"USD","in_stock":true},{"title":"3\" × 3\" \/ White","offer_id":50964068565095,"sku":"47620748176574367498","price":6.99,"currency_code":"USD","in_stock":true},{"title":"4\" × 4\" \/ White","offer_id":50964068597863,"sku":"29058844782383730755","price":8.99,"currency_code":"USD","in_stock":true},{"title":"6\" × 6\" \/ White","offer_id":50964068630631,"sku":"30612565803268402979","price":11.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0596\/8746\/9159\/files\/18224588802807298095_1200.jpg?v=1793659164","url":"https:\/\/pixelatedphysics.com\/nl\/products\/paddlewheel-joule","provider":"Pixelated Physics","version":"1.0","type":"link"}