Ingaba inobunzima bekhilogram? Izazinzulu ziye zahlola le ngxaki ibonakala ilula kangangamakhulu eminyaka.
Ngowe-1795, iFransi yamisela umthetho owawusithi “igram” “bubunzima obupheleleyo bamanzi kwityhubhu enomthamo olingana nekhulu lemitha kwiqondo lobushushu xa kunyibilika umkhenkce (oko kukuthi, ngu-0°C).” Ngo-1799, izazinzulu zafumanisa ukuba umthamo wamanzi ngowona uzinzile xa ubuninzi bamanzi buphezulu kwi-4 ° C, ngoko ke inkcazo yekhilogram itshintshile "kubunzima be-1 cubic decimeter yamanzi acocekileyo kwi-4 ° C. ”. Oku kuvelise ikhilogram yeplatinam esulungekileyo, ikhilogram ichazwa njengelingana nobunzima bayo, ebizwa ngokuba yikhilogram yogcino.
Le kilogram yovimba isetyenziswe njengomlinganiselo iminyaka engama-90. Ngowe-1889, iNkomfa yokuQala yamazwe ngamazwe kwiMetrology yavuma i-platinum-iridium alloy replica ekufutshane nekhilogram yogcino njengekhilogram yamazwe ngamazwe. Ubunzima be "kilogram" buchazwa nge-platinum-iridium alloy (90% platinum, 10% iridium) cylinder, emalunga ne-39 mm ubude kunye nobubanzi, kwaye ngoku igcinwe kwindawo engaphantsi ngaphandle kweParis.
Ikhilogram yoqobo yamazwe ngamazwe
Ukusukela kwiXesha lokuKhanya, uluntu oluvavanyayo luzibophelele ekusekeni inkqubo yovavanyo lwehlabathi. Nangona kuyindlela enokwenzeka yokusebenzisa into ebonakalayo njengebhentshi yokulinganisa, ngenxa yokuba into ebonakalayo yonakaliswa lula ngumntu okanye izinto zokusingqongileyo, ukuzinza kuya kuchaphazeleka, kwaye uluntu lokulinganisa luhlala lufuna ukushiya le ndlela ngokukhawuleza. kangangoko kunokwenzeka.
Emva kokuba ikhilogram yamkele inkcazo yekhilogram yamazwe ngamazwe, kukho umbuzo othi i-metrologists ixhalabele kakhulu: izinzile kangakanani le nkcazo? Ngaba iya kukhukuliseka ngokuhamba kwexesha?
Kufuneka kuthiwe lo mbuzo uphakanyiswe ekuqaleni kwenkcazo ye-kilogram yeyunithi yobunzima. Ngokomzekelo, xa i-kilogram yachazwa ngo-1889, i-International Bureau of Weights and Measures yavelisa i-7 platinum-iridium alloy kilogram weights, enye yazo yi-International Ikhilogram yokuqala isetyenziselwa ukuchaza ubunzima beyunithi yekhilogram, kunye nezinye ii-6 zobunzima. yenziwe ngezinto ezifanayo kunye nenkqubo efanayo isetyenziswa njengeebenchmarks zesibini ukujonga ukuba kukho i-drift ekuhambeni kwexesha phakathi komnye nomnye.
Ngexesha elifanayo, kunye nokuphuhliswa kobuchwepheshe obuchanekileyo, sifuna kwakhona imilinganiselo ezinzileyo kunye nechanekileyo. Ngoko ke, isicwangciso sokuchaza ngokutsha iyunithi esisiseko yamazwe ngamazwe enokuguquguquka ngokomzimba kwacetywa. Ukusebenzisa izinto eziguquguqukayo ukuchaza iiyunithi zomlinganiselo kuthetha ukuba ezi nkcazelo ziyakuhlangabezana neemfuno zesizukulwana esilandelayo sokufunyaniswa kwenzululwazi.
Ngokutsho kwedatha esemthethweni ye-International Bureau of Weights and Measures, kwiminyaka eyi-100 ukusuka kwi-1889 ukuya kwi-2014, ukuhambelana komgangatho wezinye iikhilogram zangaphambili kunye nekhilogram yamazwe ngamazwe yatshintshile malunga ne-50 micrograms. Oku kubonisa ukuba kukho ingxaki ngokuzinza kwebenchmark ebonakalayo yeyunithi yomgangatho. Nangona utshintsho lwe-50 micrograms luvakala luncinci, lunempembelelo enkulu kwamanye amashishini aphezulu.
Ukuba iziseko zomzimba ezisisiseko zisetyenziselwa ukutshintsha ikhilogram yokulinganisa ngokomzimba, ukuzinza kweyunithi yobunzima akuyi kuchaphazeleka sisithuba kunye nexesha. Ngoko ke, kwi-2005, i-International Committee for Weights and Measures yaqulunqa isakhelo sokusetyenziswa kwezinto ezisisiseko zenyama ukuze kuchazwe ezinye iiyunithi ezisisiseko ze-International System of Units. Kwenziwa isincomo sokuba iPlanck isoloko isetyenziswa ukuchaza ubunzima beyunithi yekhilogram, kwaye iilabhoratri zomgangatho wesizwe ezinobuchule ziyakhuthazwa ukuba zenze umsebenzi wophando lwezenzululwazi onxulumeneyo.
Ngoko ke, kwiNgqungquthela yeZizwe ngezizwe ye-2018 kwi-Metrology, izazinzulu zivotele ukuyeka ngokusemthethweni i-prototype kilogram yamazwe ngamazwe, kwaye yatshintsha i-Planck constant (uphawu h) njengomgangatho omtsha wokuphinda uchaze "kg".
Ixesha lokuposa: Mar-05-2021