Kilogram (lambangnakg) nyaétaunit dasar SI pikeunmassa. Sa-gram diwatesan ku sapersaréwu kilogram.Konversi unit ngagambarkeun unit ékivalén massa dina sistim séjén.
Émbohan SI dipaké pikeun méré ngaran tikelan atawa babagian tina kilogram. Nu ilahar dipaké nyaéta,
- ton =1 000 kg (kuduna mah disebutnamégagram, ngan jarang pisan dipaké) (kadé pahili jeungUSshort ton, 2000 pon atawa kira 907 kg)
- gram =1/1 000 kg
- milligram =sapersaréwu gram =sapersayuta kilogram
- mikrogram =sapersayuta gram =1/(10^9) kg
Kilogram mangrupa hiji-hijina unit SI nu masih kénéh watesanana dihubungkeun jeung artéfak batan sipat fisik.
Kilogrampituinna diwatesan salaku massasalétercimurni dinatemperatur 4 darajatCelsius jeungtekenan atmosfir baku.Watesan ieu hésé pisan diwujudkeun sacara akurat, salah sahijina sabab dénsitas cai gumantung kana tekenan, sedengkeun unit tekenan ngawengku massa salaku salah sahiji faktorna, antukna ngagasilkeunkagumantungan sirkular dina watesan kilogram.
Pikeun nyingkahan masalah ieu, watesan kilogram dibaru deui sacaratepat massa hijibaku husus nu dijieun sasarua-saruana jeung watesan asalna. Saprak1889, sistimSI ngawatesan unit ieu sarua jeung massaprototipe kilogram internasional, nu dijieun tina watangalloyplatinum jeungiridium nu panjang jeung diaméterna39 mm, sarta diteundeun diBiro Internasional Timbangan jeung Ukuran. Salinan resmi prototipe kilogram dijieun pikeun prototipe nasional, nu dibandingkeun jeung prototipe Paris ("Le Grand Kilo"), kasarna unggal10 taun. Prototipe kilogram internasional dijieun taun1880-an.
Dumasar watesan, kasalahan dina kabisaulangan watesan kiwari téh enol; ngan, dina harti ilahar kecapna, aya dina rentang 2mikrogram. Ieu bisa kapanggih mun urang ngabandingkeun baku jeung salinan resmina, nu dijieun tina bahan sarta diteundeun dina kaayaan nu sarua. euweuh nu bisa mastikeun mana nu leuwih stabil, naha nu asli aatawa nu salinanana. Ku kituna, prosedur ieu dipigawé unggal opat puluh taun.
Prototipe internasional kilogram sigana ngahampangan kira 50 mikrogram salila saabad ieu, ku sabab nu tacan kanyahoan (dilaporkeun dinaDer Spiegel, 2003 #26). Bébédaan nu kapanggih dina prototipena nyedek kana perluna néangan watesan anyar kilogram. Najan bener mun disebut yén sadaya objék di mayapada nambahan massana 50 mikrogram per kilogramna, sawangan ieu patojaiyah jeung ngéléhkeun tujuan unit baku massa.
Aya sawatara usaha pikeun ngawanohkeun hiji watesan tina jalan fundaméntal atawa konstanta atomik:
- TheWatt balance uses thecurrent balance that formerly was used to define theampere to relate the kilogram to a value forPlanck's constant, based on the definitions of thevolt and theohm.
- TheAvogadro approach attempts at defining the kilogram by a fixed count ofsilicon atoms. As a practical réalization, asphere will be used where the size is méasured byinterferometry.
- Theion accumulation approach involves accumulation ofgold atoms and méasuring the electrical current required to neutralise them.
- The levitatedsuperconductor approach relates the kilogram to electrical quantities by levitating a superconducting body in a magnetic field generated by a superconducting coil, and méasuring theelectrical current required in the coil.
- Since the values of theJosephson (CIPM (1988) Recommendation 1, PV 56; 19) andvon Klitzing (CIPM (1988), Recommendation 2, PV 56; 20) constants have been given conventional values, it is possible to combine these values (KJ ≡ 4.835 979×1014 Hz/V and RK ≡ 2.581 280 7×104 Ω) with the definition of theampere to define the kilogram. As follows:
- The kilogram is the mass which would be accelerated at precisely 2×10-7 m/s² if subjected to the per metre force between two straight parallel conductors of infinite length, of negligible circular cross section, placed 1 metre apart in vacuum, through which flow a constant current of exactly 6.241 509 629 152 65 × 1018 elementary charges per second.
Nalika sipat hiji barang disebutkeun dina kilogram, sipat ieu nujul ampir salawasna ka massa, padahal sipat dina pamakéan sapopoé mindengna disebut "beurat", a usage much deprecated by those communities (physicists and engineers) that preferweight always to méan "gravitational force". Occasionally the gravitational force on an object is given in "kilograms", but the unit used is not a true kilogram: it is the deprecated kilogram-force (kgf), also known as thekilopond (kp). An object of mass 1 kg at the surface of theEarth will be subjected to a gravitational force (that is to say, it will have a weight) of approximately:
- 1 kgf = 1 kg × 9,806 65 m/s² = 9.806 65N
nu mana N salakuNewton, unit gaya SI. Catet yén faktor 9,806 65 ngan disatujuan salaku rataan (CGPM ka-3 (1901), CR 70), salaku niléy tepatg, laju gravitasi lokal, béda-béda gumantung luhur-handap sarta tempatna diBumi. (Tempograviti baku).
