{"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\/fi\/gravity\/","title":{"rendered":"Painovoima!"},"content":{"rendered":"<div class=\"lede\">\n<p>Oletko koskaan n\u00e4hnyt hedelm\u00e4\u00e4 tai esinett\u00e4 putoavan puusta? Ent\u00e4 oletko koskaan yritt\u00e4nyt heitt\u00e4\u00e4 kive\u00e4 ja katsella, kuinka se putoaa? T\u00e4t\u00e4 voimaa, joka \u2018vet\u00e4\u00e4\u2019 esineit\u00e4 alas, kutsutaan painovoimaksi.<\/p>\n<\/div>\n<p>Maapallon painovoima vet\u00e4\u00e4 meit\u00e4 jatkuvasti puoleensa. Juuri siksi pysymme aina jaloillamme maassa. Meid\u00e4n ei kuitenkaan tarvitse olla suorassa kosketuksessa Maahan, jotta se vet\u00e4isi meit\u00e4 puoleensa; riitt\u00e4\u00e4, ett\u00e4 emme ole liian kaukana, jotta samat voimat vaikuttavat. T\u00e4st\u00e4 syyst\u00e4 oma planeettamme kiert\u00e4\u00e4 Aurinkoa ja Kuu kiert\u00e4\u00e4 Maata.<\/p>\n<p>Painovoima m\u00e4\u00e4r\u00e4ytyy kappaleen massan perusteella. Kahden kappaleen v\u00e4linen painovoima on verrannollinen kappaleiden massaan, ja se pienenee eritt\u00e4in nopeasti heti, kun ne erotetaan toisistaan. Itse asiassa mekin vet\u00e4mme kappaleita puoleemme \u2018omalla\u2019 painovoimallamme, mutta olemme liian kevyit\u00e4, jotta voisimme havaita sen vaikutuksia! Aurinko on kuitenkin niin suuri, ett\u00e4 se pystyy pit\u00e4m\u00e4\u00e4n meid\u00e4t l\u00e4hell\u00e4, vaikka se onkin niin kaukana. My\u00f6s Kuu vaikuttaa painovoimallaan; koska se on pienempi ja kevyempi kuin Maa, jos voisimme punnita itsemme siell\u00e4, huomaaisimme painavamme noin kuudesosan siit\u00e4, mit\u00e4 painamme Maassa.<\/p>\n<p>Voisi kysy\u00e4, miksi Kuu ei putoa Maahan kuten omena puusta. Syyn\u00e4 on se, ett\u00e4 Kuu ei ole koskaan paikallaan. Se liikkuu jatkuvasti ymp\u00e4rill\u00e4mme. Ilman Maan painovoimaa se vain leijuisi pois avaruuteen. T\u00e4m\u00e4 nopeuden ja Maasta mitatun et\u00e4isyyden yhdistelm\u00e4 pit\u00e4\u00e4 Kuun aina tasapainossa putoamisen ja pakenemisen v\u00e4lill\u00e4. Jos se olisi nopeampi, se pakenisi; jos se olisi hitaampi, se putoaisi!<\/p>\n<p>Sanoimme, ett\u00e4 painovoima riippuu my\u00f6s et\u00e4isyydest\u00e4. Jos p\u00e4\u00e4sisimme riitt\u00e4v\u00e4n kauas, voisimme vapautua sen otteesta. Juuri sit\u00e4 yrit\u00e4mme tehd\u00e4 avaruusaluksilla. Meid\u00e4n on saavutettava ja ylitett\u00e4v\u00e4 niin sanottu \u2018pakonopeus\u2019, joka on noin 11,2 km\/s (t\u00e4ll\u00e4 nopeudella voisimme matkustaa Lontoosta New Yorkiin vain kymmeness\u00e4 minuutissa!). Kun avaruussukkula saavuttaa t\u00e4m\u00e4n nopeuden, se voi liikkua vapaasti aurinkokunnassa.<\/p>\n<p>Kiertoradalla olevassa avaruussukkulassa emme tunne Maan painovoimaa. Esineet eiv\u00e4t putoa, vaan leijuvat; jos hypp\u00e4\u00e4t yl\u00f6s, et tule takaisin alas. Sama tapahtuu astronautille, kun he ovat Maata kiert\u00e4vill\u00e4 avaruusasemilla!<\/p>\n<nav class=\"related\" aria-label=\"Aiheeseen liittyv\u00e4t\">\n<h2 class=\"related__heading\">Aiheeseen liittyv\u00e4t<\/h2>\n<div class=\"grid related__grid\">\n<div class=\"grid-item\">\n<article class=\"card focuson agency\"><a class=\"card__link\" href=\"\/fi\/maanen_jorden_og_tyngdekraften2\/\"><\/p>\n<figure class=\"thumbnail\"><span class=\"dimmer\"><\/span><\/figure>\n<header class=\"entry\">\n<h3 class=\"heading\">Tanska<\/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=\"\/fi\/de_maan_de_aarde_en_zwaartekracht\/\"><\/p>\n<figure class=\"thumbnail\"><span class=\"dimmer\"><\/span><\/figure>\n<header class=\"entry\">\n<h3 class=\"heading\">hollanti<\/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=\"\/fi\/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\">ranska<\/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=\"\/fi\/mond_erde_und_schwerkraft\/\"><\/p>\n<figure class=\"thumbnail\"><span class=\"dimmer\"><\/span><\/figure>\n<header class=\"entry\">\n<h3 class=\"heading\">saksa<\/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=\"\/fi\/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\">italia<\/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=\"\/fi\/maanen_jorden_og_tyngdekraften\/\"><\/p>\n<figure class=\"thumbnail\"><span class=\"dimmer\"><\/span><\/figure>\n<header class=\"entry\">\n<h3 class=\"heading\">norja<\/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=\"\/fi\/ksiezyc_ziemia_i_grawitacja\/\"><\/p>\n<figure class=\"thumbnail\"><span class=\"dimmer\"><\/span><\/figure>\n<header class=\"entry\">\n<h3 class=\"heading\">puola<\/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=\"\/fi\/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\">espanja<\/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=\"\/fi\/maanen_jorden_och_gravitation\/\"><\/p>\n<figure class=\"thumbnail\"><span class=\"dimmer\"><\/span><\/figure>\n<header class=\"entry\">\n<h3 class=\"heading\">ruotsi<\/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\/fi\/wp-json\/wp\/v2\/posts\/484","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/users\/5"}],"replies":[{"embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/comments?post=484"}],"version-history":[{"count":1,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/posts\/484\/revisions"}],"predecessor-version":[{"id":1627,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/posts\/484\/revisions\/1627"}],"wp:attachment":[{"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/media?parent=484"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/categories?post=484"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/tags?post=484"},{"taxonomy":"panel","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/panel?post=484"},{"taxonomy":"language","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/language?post=484"},{"taxonomy":"age","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/age?post=484"},{"taxonomy":"duration","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/duration?post=484"},{"taxonomy":"resource_type","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/resource_type?post=484"},{"taxonomy":"audience","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/audience?post=484"},{"taxonomy":"wf_post_folders","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/wf_post_folders?post=484"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}