Yuav ua li cas los sib piv qhov tseem ceeb: kauj ruam yog kauj ruam cov lus qhia. Yuav ua li cas tseem ceeb yuav muab piv: piv txwv

Los ntawm cov ancient lub sij hawm, cov neeg tiag xav nyob rau hauv cov nqe lus nug ntawm yuav ua li cas nws yog qhov zoo tshaj los sib piv qhov tseem ceeb hais nyob rau hauv txawv qhov tseem ceeb. Thiab nws tsis yog cia li tej yam ntuj tso kev xav. Txiv neej ancient ntiaj teb civilizations muab nws ib tug heev yooj yim ntaub ntawv purely tswv yim muaj nuj nqis. Puas tu yog ntsuas hauv av, txiav txim tus luj ntawm cov khoom rau lub lag luam, koj yuav tau xam tus piv ntawm cov khoom nyob rau hauv barter, los mus txiav txim qhov tseeb tus nqi ntawm lub txiv hmab thaum lub sij hawm sau qoob loo ntawm cawu cub - cov no yog cov cia li ib tug me me ib feem ntawm kev pab raws qib uas feem ntau surfaced nyob rau hauv ib tug twb nyuaj lub neej ntawm peb cov pog koob yawg koob. Yog li ntawd, tsis zoo lub kawm thiab tsis paub ntawv cov neeg los sib piv, yog tias tsim nyog, qhov tseem ceeb ua raws li lub tswv yim ntawm nws ntau txog tej comrades, thiab lawv feem ntau noj lub uas tsim nyog recompense rau qhov kev pab no, thiab zoo zoo nkauj, los ntawm txoj kev.

Yuav ua li cas yuav muab piv

Nyob rau hauv peb lub sij hawm, qhov no txoj hauj lwm yog tseem muab ib tug txiav txim luag hauj lwm nyob rau hauv txoj kev tshawb no ntawm lub caij nyoog sciences. Txhua leej txhua tus, ntawm chav kawm, peb paub hais tias nws yog tsim nyog los sib piv cov nqi ntawm homogeneous, piv txwv li apples - apples thiab beets - nrog beets. Leej twg thiab yuav tsis sim qhia Celsius nyob rau hauv kilometers los yog kilograms nyob rau hauv decibels, tab sis lub boa ntev parrots peb paub los ntawm thaum yau (rau cov neeg uas tsis nco qab, nyob rau hauv ib tug boa - 38 parrots). Txawm tias parrots, dhau lawm, yog sib txawv, thiab nyob rau hauv qhov tseeb boa ntev yuav sib txawv nyob ntawm seb lub subspecies ntawm lub leeb nkaub, tab sis cov no yog cov ntsiab lus nyob rau hauv uas peb yuav ua tiag kom koj to taub.

dimensionality

Thaum nyob rau hauv txoj hauj lwm: "Muab piv rau qhov tseem ceeb" yuav tsum yog cov neeg tib qhov tseem ceeb ua rau ib qho denominator, uas yog qhia nyob rau hauv tib lub qhov tseem ceeb rau yooj yim ntawm kev sib piv. Nws yog tseeb hais tias los sib piv cov nqi, qhia nyob rau hauv kilograms nrog ib tug nqi qhia nyob rau hauv centners los yog nyob rau hauv tons, rau ntau ntawm peb nyob rau hauv lub cellar. Txawm li cas los, muaj homogeneous ntau uas yuav tau qhia nyob rau hauv ntev ntau yam thiab, tas, nyob rau hauv sib txawv xab tshuab. Sim, piv txwv li, piv rau qhov tseem ceeb ntawm kinematic viscosity thiab txiav txim seb yog dej khov dua cov kua nyob rau hauv CST thiab square meters ib ob. Nws tsis ua hauj lwm? Thiab tsis tau. Ua li no, ob leeg qhov tseem ceeb muaj kev cuam tshuam rau tib lub qhov tseem ceeb, thiab twb nyob rau numeric tus nqi los mus txiav txim uas lawv yog superior rau tus nrog sib ntaus.

tsoov system

Nyob rau hauv thiaj li yuav to taub li cas tseem ceeb yuav muab piv, sim kom rov qab uas twb muaj lawm ntsuas system. Nyob rau hauv kev txiav txim rau optimize thiab leeb lub zos cov txheej txheem nyob rau hauv 1875, kaum xya lub teb chaws (xws li Russia, teb chaws USA, Lub teb chaws Yelemees thiab lwm tus neeg.) Tau kos npe los ntawm lub 'meter' Convention thiab txiav txim metric system. Yuav kom tsim thiab sau cov qauv ntawm lub 'meter' thiab cov kilogram twb nrhiav tau lub International Committee rau tes taw hnyav li thiab ntsuas, thiab nyob rau hauv Paris, rau equip lub International Bureau of tes taw hnyav li thiab ntsuas. Qhov no system nws thiaj li hloov zuj zuj mus rau hauv lub International System of Chav, SI. Tam sim no, qhov no muaj tau txais yuav los ntawm ntau lub teb chaws nyob rau hauv lub tshav pob ntawm kev xam, xws li cov teb chaws nyob qhov twg feeb teb chaws siv nyob rau hauv txhua txhua hnub lub neej lub cev ntau (xws li lub tebchaws United States thiab hais).

GHS

Txawm li cas los, nyob rau hauv thaum uas tig mus nrog cov pa siv cov qauv los tsim lwm yam, tsawg yooj yim CGS system (centimeter-gram-thib ob). Nws twb npaj siab nyob rau hauv 1832 los ntawm tus German physicist Gauss, thiab nyob rau hauv 1874 upgraded Maxwell thiab Thompson, mas nyob rau hauv lub teb ntawm electrodynamics. Nyob rau hauv 1889 nws tau muaj ntau yooj yim MKS system (meter-kilogram-thib ob). Piv coob siv tus nqi meter thiab kilogram engineers ntau npaum li cas yooj yim tshaj txoj kev siv cov derivatives (centi-, milli-, deci- li al.). Txawm li cas los, cov tswvyim no tsis tau pom ib tug loj heev teb nyob rau hauv lub siab lub ntsws ntawm cov uas nws twb npaj. Thoob plaws hauv lub ntiaj teb no, kev koom tsim thiab siv metric system, yog li cov lus teb los ntawm cov GHS thiab tsawg tsawg, thiab tom qab 1960, nrog cov kev taw qhia ntawm cov SI system, GHS thiab suab poob mus rau hauv disuse. Tam sim no GHS tau thov nyob rau hauv kev xyaum tsuas yog tias cov lus teb nyob rau hauv theoretical mechanics thiab astrophysics, thiab ces vim muaj ib tug yooj yim daim ntawv cov ntaubntawv povthawj siv kev cai ntawm electromagnetism.

Kauj ruam yog kauj ruam qhia

Cia peb kawm nyob rau hauv kom meej ib qho piv txwv. Piv txwv qhov teeb meem yog: "Koj muaj peev xwm muab piv rau tus nqi ntawm 25 tons thiab 19570 kg seb qhov twg yog qhov ntau dua.?" Yuav ua li cas yuav tsum tau koj ua ntej tshaj plaws yog los mus txiav txim nyob rau hauv dab tsi tseem ceeb peb yog muab qhov tseem ceeb. Yog li ntawd, cov thawj nqi uas peb tau muab nyob rau hauv tonnes, thiab lub thib ob - nyob rau hauv kilograms. Nyob rau hauv lub kauj ruam thib ob, peb xyuas seb peb yuav tsis ua rau nkag mus rau ib tug ruam tag hauj lwm compilers, ua kom tau los sib piv txawv qhov tseem ceeb. Tseem muaj txoj hauj lwm-cuab, tshwj xeeb tshaj yog nyob rau hauv lub ceev ceev mus kuaj, qhov twg cov lus teb rau txhua lo lus nug yog muab rau 20-30 vib nas this. Raws li peb tau pom, rau qhov tseem ceeb yog uniform: nyob rau hauv kilograms thiab tonnes peb tau ntsuas lub loj thiab lub cev hnyav, li ntawd, qhov thib ob xeem yog dhau nrog ib tug zoo tshwm sim. Qhov thib peb kauj ruam, txhais kilograms mus rau ib tug ton, los yog, conversely, ib tug ton - nyob rau hauv kilograms rau yooj yim ntawm kev sib piv. Nyob rau hauv thawj embodiment puv 25 thiab 19,57 tons, thiab ob: 25 000 thiab 19 570 kg. Thiab tam sim no koj muaj peev xwm nrog kev thaj yeeb ntawm lub hlwb los sib piv qhov tseem ceeb ntawm cov qhov tseem ceeb. Raws li kom meej meej pom, thawj tus nqi (25 m) nyob rau hauv ob leeg yog ntau dua qhov thib ob (19 570 kg).

cuab

Raws li hais saum toj no, niaj hnub ntsuam xyuas muaj ib tug ntau ntawm txoj hauj lwm-bogus. Qhov no yog tsis tas parsed peb ua hauj lwm, ib tug cuab yuav ua tau heev txawm-nrhiav lo lus nug, tshwj xeeb tshaj yog ib tug uas begs ib zajlus kom teb. Txawm li cas los, lub perfidy, raws li ib tug txoj cai, yog nyob rau hauv cov lus, los yog nyob rau hauv ib tug me me nuance hais tias cov drafters ntawm txoj hauj lwm yog ua nyob rau hauv txhua txoj kev uas ua zam. Piv txwv li, es tsis txhob ntawm tus paub koj ib tug disassembled teeb meem nrog lub formulation ntawm cov nqe lus nug: "Sib piv cov nqi qhov twg nws yog tau" - lub drafters ntawm qhov kev kuaj muaj peev xwm tsuas thov kom koj los sib piv cov qhov tseem ceeb thiab xaiv qhov tseem ceeb rau lawv tus kheej yog strikingly zoo xws li cov txhua lwm yam. Piv txwv li, kg * m / s thiab ² m / s ^2. Nyob rau hauv thawj rooj plaub no nws yog tus quab yuam sawv rau tus kwv (Newtons), thiab lub thib ob - acceleration ntawm lub cev, los yog m / s thiab ² m / s nyob qhov twg koj yuav tau los sib piv cov acceleration ntawm cov kev ceev ntawm lub cev, uas yog lig txawv qhov tseem ceeb.

complex sib piv

Txawm li cas los, ntau heev nyob rau hauv cov hauj lwm ua ob qhov tseem ceeb, qhia tsis tau tsuas yog nyob rau hauv qhov sib txawv cov chav nyob thiab sib txawv systems ntawm xam, tab sis kuj sib txawv los ntawm txhua lwm yam nyob rau lub specifics ntawm lub cev lub ntsiab lus. Piv txwv li, nyob rau hauv qhov teeb meem tsab ntawv nws hais tias: "Muab piv rau qhov tseem ceeb ntawm dynamic thiab kinematic viscosity thiab txiav txim seb yog dej khov dua kua." Qhov tseem ceeb ntawm kinematic viscosity yog muab nyob rau hauv SI units, uas yog, nyob rau hauv m ² / s, thiab dynamic - lub GHS, uas yog, nyob rau hauv poise. Yuav ua li cas nyob rau hauv cov ntaub ntawv no?

Yuav kom daws tau cov teeb meem no, koj muaj peev xwm siv lub saum toj no cov lus qhia nrog ib tug me me ntxiv nws. Peb txiav txim uas ntawm lub tshuab yuav ua hauj lwm: cia nws yuav tus SI system, yog ib qho ntawm cov engineers. Cov kauj ruam thib ob, peb kuj mus saib thiab pom tau tias nws yog ib tug cuab? Tab sis nyob rau hauv qhov kev piv txwv, ib yam nkaus thiab, txhua yam yog huv si. Peb sib piv cov ob kua cov parameter ntawm tus nrog sib txhuam (viscosity), txawm li cas los ob leeg qhov tseem ceeb yog homogeneous. Qhov thib peb kauj ruam ntawm txhais cov dynamic viscosity ntawm poise nyob rau hauv Pascal-ob, uas yog nyob rau hauv ntau chav nyob ntawm lub SI system. Ntxiv txhais ib kinematic viscosity nyob rau hauv ib tug dynamic, txawj nws los ntawm cov coj tus nqi ntawm cov kua ceev (rooj tus nqi) thiab muab piv rau qhov kev tshwm sim tau.

sab nraum lub system

Muaj kuj tsis yog-SI units, piv txwv li chav nyob tsis muaj nyob rau hauv SI, tab sis raws li kev soj ntsuam ntawm convening lub Tuam Rooj Sab Laj txiav txim siab rau tes taw hnyav li thiab ntsuas (GKVM), siv tau rau cov SI. Piv cov qhov tseem ceeb rau txhua tus lwm yam tsuas yog thaum coj lawv mus rau ib tug ntau mean SI txheem. Mus rau sab nraum lub system muaj xws li chav nyob xws li cov feeb, teev, hnub, liter, electron volts, ntawm ha, bar, Angstrom, thiab ntau lwm tus neeg.