{"id":396,"date":"2017-11-29T19:22:52","date_gmt":"2017-11-29T19:22:52","guid":{"rendered":"http:\/\/institutviladomat.cat\/portfoli\/16marcduran\/?p=396"},"modified":"2017-11-29T19:32:41","modified_gmt":"2017-11-29T19:32:41","slug":"la-teoria-de-les-dimensions","status":"publish","type":"post","link":"https:\/\/institutviladomat.cat\/portfoli\/16marcduran\/general\/curs-2017-2018\/la-teoria-de-les-dimensions\/","title":{"rendered":"La teoria de les dimensions"},"content":{"rendered":"

1.-<\/span>\u00a0Celeritat, despla\u00e7ament i velocitat<\/p>\n

La unitat de celeritat mitjana \u00e9s el metre per segon (m\/s) i la unitat usual es U.S.A. \u00e9s el peu per segon (ft<\/span>\/s). Una altra unitat coneguda \u00e9s el kil\u00f2metre per hora (km\/h). Si condu\u00efm\u00a0200km<\/span>\u00a0en\u00a05h<\/span>.\u00a0la<\/span>\u00a0nostra celeritat ser\u00e0 de\u00a0200km<\/span>\/5h<\/span>\u00a0= 40 km\/h.<\/p>\n

Podem saber que hi ha condu\u00eft constantment a 40 km\/h durant les\u00a05h<\/span>.\u00a0o<\/span>\u00a0pot haver anat m\u00e9s\u00a0de pressa\u00a0en alguns moments del trajecte i mes a poc a poc en unes altres parts. O es podria haver parat durant una hora una \u00e0rea de servei,\u00a0\u00e9s\u00a0a dir que hi ha una variable en el temps.<\/p>\n

El concepte de velocitat,\u00a0\u00e9s\u00a0semblant al de celeritat, si\u00a0b\u00e9\u00a0difereix\u00a0en el fet que\u00a0inclou la direcci\u00f3\u00a0i\u00a0el sentit.<\/p>\n

\"ResultatSuposem que el cotxe est\u00e0 en la posici\u00f3\u00a0x1<\/span>\u00a0en un temps\u00a0t2<\/span>\u00a0i en un punt\u00a0x2<\/span>\u00a0en un temps\u00a0t2<\/span>. La variaci\u00f3 de la posici\u00f3 de la part\u00edcula,\u00a0x2<\/span>\u00a0–\u00a0x1<\/span>, rep el nom de\u00a0despla\u00e7ament\u00a0de la part\u00edcula (fig. 2-1). S’acostuma a utilitzar la lletra grega \u0394 (delta maj\u00fascula) per indicar la variaci\u00f3 d’una quantitat. Aix\u00ed llavors, la variaci\u00f3 de x s’escriur\u00e0\u00a0\u0394x<\/span>:<\/p>\n

\u0394x<\/span>=x2<\/span>–x1<\/span><\/p>\n

La notaci\u00f3\u00a0\u0394x<\/span>\u00a0representa per una sola quantitat, la variaci\u00f3 x. No\u00a0es<\/span>\u00a0un producte per\u00a0\u0394x<\/span>\u00a0amb cos no\u00a0es<\/span>\u00a0un producte de cos per\u00a0\u03b8<\/span>.<\/p>\n

La velocitat de la variaci\u00f3, per unitat de temps, de la posici\u00f3. La velocitat mitjana\u00a0de les part\u00edcules, per definici\u00f3 la ra\u00f3 del despla\u00e7ament.\u00a0x<\/span>\u00a0a l’interval de temps:<\/p>\n

\u0394t<\/span>\u00a0=\u00a0t2<\/span>\u00a0—\u00a0t1<\/span><\/p>\n

\u039emed<\/span>=xt<\/span>=x2<\/span>–x1t2<\/span>–t1<\/span><\/p>\n

Exemple.<\/p>\n

Un cargol, est\u00e0 entre\u00a0x1<\/span>\u00a0=\u00a018mm<\/span>\u00a0en\u00a0t1<\/span>\u00a0=\u00a02s<\/span>\u00a0i el trobem posteriorment a\u00a0x2 14mm<\/span>\u00a0en\u00a0t2<\/span>\u00a0=\u00a07s<\/span>. Trobar el\u00a0despla\u00e7ament\u00a0i la velocitat mitjana del\u00a0cargol<\/span>\u00a0en aquest interval de temps.<\/p>\n

Segons\u00a0la definici\u00f3, el\u00a0despla\u00e7ament\u00a0del\u00a0cargol<\/span>\u00a0es<\/p>\n

x =x2<\/span>–\u00a0x1<\/span>=\u00a014mm<\/span>–18mm<\/span>=(-4mm<\/span>)<\/p>\n

\u039emed<\/span>=xt<\/span>=x2<\/span>–x1t2<\/span>–t1<\/span>=14mm<\/span>\u00a0–\u00a018mm7s<\/span>\u00a0–2s<\/span>–4mm5s<\/span>= –0.8mm<\/span>\/s<\/span><\/p>\n

Per saber-hi m\u00e8s>>><\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

1.-\u00a0Celeritat, despla\u00e7ament i velocitat La unitat de celeritat mitjana \u00e9s el metre per segon (m\/s) i la unitat usual es U.S.A. \u00e9s el peu per segon (ft\/s). Una…<\/p>\n","protected":false},"author":86,"featured_media":397,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[27,37],"tags":[],"_links":{"self":[{"href":"https:\/\/institutviladomat.cat\/portfoli\/16marcduran\/wp-json\/wp\/v2\/posts\/396"}],"collection":[{"href":"https:\/\/institutviladomat.cat\/portfoli\/16marcduran\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/institutviladomat.cat\/portfoli\/16marcduran\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/institutviladomat.cat\/portfoli\/16marcduran\/wp-json\/wp\/v2\/users\/86"}],"replies":[{"embeddable":true,"href":"https:\/\/institutviladomat.cat\/portfoli\/16marcduran\/wp-json\/wp\/v2\/comments?post=396"}],"version-history":[{"count":3,"href":"https:\/\/institutviladomat.cat\/portfoli\/16marcduran\/wp-json\/wp\/v2\/posts\/396\/revisions"}],"predecessor-version":[{"id":400,"href":"https:\/\/institutviladomat.cat\/portfoli\/16marcduran\/wp-json\/wp\/v2\/posts\/396\/revisions\/400"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/institutviladomat.cat\/portfoli\/16marcduran\/wp-json\/wp\/v2\/media\/397"}],"wp:attachment":[{"href":"https:\/\/institutviladomat.cat\/portfoli\/16marcduran\/wp-json\/wp\/v2\/media?parent=396"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/institutviladomat.cat\/portfoli\/16marcduran\/wp-json\/wp\/v2\/categories?post=396"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/institutviladomat.cat\/portfoli\/16marcduran\/wp-json\/wp\/v2\/tags?post=396"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}