{"id":484,"date":"2016-06-06T07:56:00","date_gmt":"2016-06-06T05:56:00","guid":{"rendered":"https:\/\/kids.esa.int\/gravity\/"},"modified":"2026-10-08T00:28:44","modified_gmt":"2026-10-07T22:28:44","slug":"gravity","status":"publish","type":"post","link":"https:\/\/kids.esa.int\/ro\/gravity\/","title":{"rendered":"Gravita\u021bia!"},"content":{"rendered":"<div class=\"lede\">\n<p>Ai v\u0103zut vreodat\u0103 un fruct sau un obiect c\u0103z\u00e2nd dintr-un copac? \u0218i ai \u00eencercat vreodat\u0103 s\u0103 arunci o piatr\u0103 \u0219i s\u0103 o prive\u0219ti cum cade? Aceast\u0103 for\u021b\u0103 care \u2018trage \u00een jos\u2019 lucrurile se nume\u0219te for\u021ba gravita\u021bional\u0103.<\/p>\n<\/div>\n<p>Suntem atra\u0219i \u00een permanen\u021b\u0103 de P\u0103m\u00e2nt prin for\u021ba sa gravita\u021bional\u0103. Acesta este motivul pentru care ne men\u021binem mereu cu picioarele pe p\u0103m\u00e2nt. Totu\u0219i, nu este nevoie s\u0103 fim \u00een contact direct cu P\u0103m\u00e2ntul pentru a fi atra\u0219i de el; este suficient s\u0103 nu fim prea departe pentru ca acelea\u0219i for\u021be s\u0103 ac\u021bioneze. De aceea, propria noastr\u0103 planet\u0103 orbiteaz\u0103 \u00een jurul Soarelui, iar Luna orbiteaz\u0103 \u00een jurul P\u0103m\u00e2ntului.<\/p>\n<p>For\u021ba gravita\u021bional\u0103 este determinat\u0103 de masa unui obiect. For\u021ba gravita\u021bional\u0103 dintre dou\u0103 obiecte este propor\u021bional\u0103 cu masa acestora \u0219i scade foarte repede \u00een momentul \u00een care le separ\u0103m. De fapt, \u0219i noi atragem obiecte cu \u2018propria\u2019 noastr\u0103 for\u021b\u0103 gravita\u021bional\u0103, dar suntem prea u\u0219ori pentru a observa efectele! Soarele, \u00eens\u0103, este at\u00e2t de mare \u00eenc\u00e2t reu\u0219e\u0219te s\u0103 ne \u021bin\u0103 aproape chiar \u0219i atunci c\u00e2nd se afl\u0103 at\u00e2t de departe. \u0218i Luna \u00ee\u0219i exercit\u0103 for\u021ba gravita\u021bional\u0103; \u00eentruc\u00e2t este mai mic\u0103 \u0219i mai u\u0219oar\u0103 dec\u00e2t P\u0103m\u00e2ntul, dac\u0103 ne-am putea c\u00e2nt\u0103ri pe ea, am descoperi c\u0103 greutatea noastr\u0103 ar fi de aproximativ o \u0219esime din cea pe care o avem pe P\u0103m\u00e2nt.<\/p>\n<p>Ne-am putea \u00eentreba de ce Luna nu cade pe P\u0103m\u00e2nt la fel cum cade un m\u0103r din copac. Motivul este c\u0103 Luna nu st\u0103 niciodat\u0103 pe loc. Se mi\u0219c\u0103 constant \u00een jurul nostru. F\u0103r\u0103 for\u021ba de gravita\u021bie a P\u0103m\u00e2ntului, ar pluti pur \u0219i simplu \u00een spa\u021biu. Aceast\u0103 combina\u021bie de vitez\u0103 \u0219i distan\u021b\u0103 fa\u021b\u0103 de P\u0103m\u00e2nt permite Lunii s\u0103 se men\u021bin\u0103 mereu \u00een echilibru \u00eentre c\u0103dere \u0219i evadare. Dac\u0103 ar fi mai rapid\u0103, ar sc\u0103pa; dac\u0103 ar fi mai lent\u0103, ar c\u0103dea!<\/p>\n<p>Am spus c\u0103 for\u021ba gravita\u021bional\u0103 depinde \u0219i de distan\u021b\u0103. Dac\u0103 ne-am \u00eendep\u0103rta suficient, am putea sc\u0103pa de atrac\u021bia ei. Asta \u00eencerc\u0103m s\u0103 facem cu navele spa\u021biale. Trebuie s\u0103 atingem \u0219i s\u0103 dep\u0103\u0219im a\u0219a-numita \u2018vitez\u0103 de evadare\u2019, care este de aproximativ 11,2 km\/s (la o astfel de vitez\u0103, am putea ajunge de la Londra la New York \u00een doar zece minute!). Odat\u0103 ce o navet\u0103 atinge aceast\u0103 vitez\u0103, ea este liber\u0103 s\u0103 c\u0103l\u0103toreasc\u0103 \u00een Sistemul Solar.<\/p>\n<p>\u00cen interiorul unei navete aflate pe orbit\u0103 nu sim\u021bim for\u021ba gravita\u021bional\u0103 a P\u0103m\u00e2ntului. Obiectele nu cad, ci plutesc; dac\u0103 sari \u00een sus, nu te mai \u00eentorci jos. Acela\u0219i lucru li se \u00eent\u00e2mpl\u0103 \u0219i astronau\u021bilor c\u00e2nd se afl\u0103 \u00een sta\u021biile spa\u021biale care orbiteaz\u0103 \u00een jurul P\u0103m\u00e2ntului!<\/p>\n<nav class=\"related\" aria-label=\"Legat de\">\n<h2 class=\"related__heading\">Legat de<\/h2>\n<div class=\"grid related__grid\">\n<div class=\"grid-item\">\n<article class=\"card focuson agency\"><a class=\"card__link\" href=\"\/ro\/maanen_jorden_og_tyngdekraften2\/\"><\/p>\n<figure class=\"thumbnail\"><span class=\"dimmer\"><\/span><\/figure>\n<header class=\"entry\">\n<h3 class=\"heading\">danez\u0103<\/h3>\n<\/header>\n<p><\/a><\/article>\n<\/div>\n<div class=\"grid-item\">\n<article class=\"card focuson agency\"><a class=\"card__link\" href=\"\/ro\/de_maan_de_aarde_en_zwaartekracht\/\"><\/p>\n<figure class=\"thumbnail\"><span class=\"dimmer\"><\/span><\/figure>\n<header class=\"entry\">\n<h3 class=\"heading\">Olandez\u0103<\/h3>\n<\/header>\n<p><\/a><\/article>\n<\/div>\n<div class=\"grid-item\">\n<article class=\"card focuson agency\"><a class=\"card__link\" href=\"\/ro\/la_lune_la_terre_et_la_gravite\/\"><\/p>\n<figure class=\"thumbnail\"><span class=\"dimmer\"><\/span><\/figure>\n<header class=\"entry\">\n<h3 class=\"heading\">Francez\u0103<\/h3>\n<\/header>\n<p><\/a><\/article>\n<\/div>\n<div class=\"grid-item\">\n<article class=\"card focuson agency\"><a class=\"card__link\" href=\"\/ro\/mond_erde_und_schwerkraft\/\"><\/p>\n<figure class=\"thumbnail\"><span class=\"dimmer\"><\/span><\/figure>\n<header class=\"entry\">\n<h3 class=\"heading\">German\u0103<\/h3>\n<\/header>\n<p><\/a><\/article>\n<\/div>\n<div class=\"grid-item\">\n<article class=\"card focuson agency\"><a class=\"card__link\" href=\"\/ro\/la_luna_la_terra_e_la_gravita\/\"><\/p>\n<figure class=\"thumbnail\"><span class=\"dimmer\"><\/span><\/figure>\n<header class=\"entry\">\n<h3 class=\"heading\">italian\u0103<\/h3>\n<\/header>\n<p><\/a><\/article>\n<\/div>\n<div class=\"grid-item\">\n<article class=\"card focuson agency\"><a class=\"card__link\" href=\"\/ro\/maanen_jorden_og_tyngdekraften\/\"><\/p>\n<figure class=\"thumbnail\"><span class=\"dimmer\"><\/span><\/figure>\n<header class=\"entry\">\n<h3 class=\"heading\">norvegian\u0103<\/h3>\n<\/header>\n<p><\/a><\/article>\n<\/div>\n<div class=\"grid-item\">\n<article class=\"card focuson agency\"><a class=\"card__link\" href=\"\/ro\/ksiezyc_ziemia_i_grawitacja\/\"><\/p>\n<figure class=\"thumbnail\"><span class=\"dimmer\"><\/span><\/figure>\n<header class=\"entry\">\n<h3 class=\"heading\">polonez\u0103<\/h3>\n<\/header>\n<p><\/a><\/article>\n<\/div>\n<div class=\"grid-item\">\n<article class=\"card focuson agency\"><a class=\"card__link\" href=\"\/ro\/la_luna_la_tierra_y_la_gravedad\/\"><\/p>\n<figure class=\"thumbnail\"><span class=\"dimmer\"><\/span><\/figure>\n<header class=\"entry\">\n<h3 class=\"heading\">Spaniol\u0103<\/h3>\n<\/header>\n<p><\/a><\/article>\n<\/div>\n<div class=\"grid-item\">\n<article class=\"card focuson agency\"><a class=\"card__link\" href=\"\/ro\/maanen_jorden_och_gravitation\/\"><\/p>\n<figure class=\"thumbnail\"><span class=\"dimmer\"><\/span><\/figure>\n<header class=\"entry\">\n<h3 class=\"heading\">Suedez\u0103<\/h3>\n<\/header>\n<p><\/a><\/article>\n<\/div>\n<\/div>\n<\/nav>","protected":false},"excerpt":{"rendered":"<p>Have you ever seen a fruit or object falling from a tree? And have you ever tried to throw a stone and watch it fall? This force that \u2018brings down\u2019 [&hellip;]<\/p>\n","protected":false},"author":5,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"esa_banner_image":"https:\/\/www.esa.int\/var\/esa\/storage\/images\/esa_multimedia\/images\/2016\/06\/gravity_apple_newton\/17897755-2-eng-GB\/Gravity_apple_Newton.jpg","esa_banner_description":"","esa_banner_credit":"ESA","esa_banner_licence":"ESA Standard Licence","esa_banner_detail_url":"https:\/\/www.esa.int\/ESA_Multimedia\/Images\/2016\/06\/Gravity_apple_Newton","esa_external_url":"","esa_external_new_window":false,"_jetpack_feature_clip_id":0,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_post_was_ever_published":true},"categories":[10,11,19],"tags":[],"panel":[],"language":[],"age":[],"duration":[],"resource_type":[],"audience":[],"wf_post_folders":[],"class_list":["post-484","post","type-post","status-publish","format-standard","hentry","category-learn","category-our-universe","category-story-of-the-universe"],"jetpack_sharing_enabled":true,"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/kids.esa.int\/ro\/wp-json\/wp\/v2\/posts\/484","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/kids.esa.int\/ro\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/kids.esa.int\/ro\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/kids.esa.int\/ro\/wp-json\/wp\/v2\/users\/5"}],"replies":[{"embeddable":true,"href":"https:\/\/kids.esa.int\/ro\/wp-json\/wp\/v2\/comments?post=484"}],"version-history":[{"count":1,"href":"https:\/\/kids.esa.int\/ro\/wp-json\/wp\/v2\/posts\/484\/revisions"}],"predecessor-version":[{"id":1627,"href":"https:\/\/kids.esa.int\/ro\/wp-json\/wp\/v2\/posts\/484\/revisions\/1627"}],"wp:attachment":[{"href":"https:\/\/kids.esa.int\/ro\/wp-json\/wp\/v2\/media?parent=484"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/kids.esa.int\/ro\/wp-json\/wp\/v2\/categories?post=484"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/kids.esa.int\/ro\/wp-json\/wp\/v2\/tags?post=484"},{"taxonomy":"panel","embeddable":true,"href":"https:\/\/kids.esa.int\/ro\/wp-json\/wp\/v2\/panel?post=484"},{"taxonomy":"language","embeddable":true,"href":"https:\/\/kids.esa.int\/ro\/wp-json\/wp\/v2\/language?post=484"},{"taxonomy":"age","embeddable":true,"href":"https:\/\/kids.esa.int\/ro\/wp-json\/wp\/v2\/age?post=484"},{"taxonomy":"duration","embeddable":true,"href":"https:\/\/kids.esa.int\/ro\/wp-json\/wp\/v2\/duration?post=484"},{"taxonomy":"resource_type","embeddable":true,"href":"https:\/\/kids.esa.int\/ro\/wp-json\/wp\/v2\/resource_type?post=484"},{"taxonomy":"audience","embeddable":true,"href":"https:\/\/kids.esa.int\/ro\/wp-json\/wp\/v2\/audience?post=484"},{"taxonomy":"wf_post_folders","embeddable":true,"href":"https:\/\/kids.esa.int\/ro\/wp-json\/wp\/v2\/wf_post_folders?post=484"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}