Cov ntsiab lus tseem ceeb ntawm kinematics yog dab tsi? Qhov no science yog dab tsi thiab nws kawm dab tsi? Niaj hnub no peb yuav tham txog dab tsi kinematics yog dab tsi, cov ntsiab lus tseem ceeb ntawm kinematics tshwm sim hauv cov dej num thiab lawv txhais li cas. Ntxiv thiab, cia peb tham txog qhov ntau uas peb feem ntau cuam tshuam nrog.
Kinematics. Basic concepts and definitions
Ua ntej, cia peb tham txog qhov nws yog dab tsi. Ib qho kev kawm feem ntau ntawm physics hauv tsev kawm ntawv cov chav kawm yog mechanics. Nws tau ua raws li kev txiav txim tsis tiav los ntawm molecular physics, hluav taws xob, optics, thiab lwm yam ceg, xws li, piv txwv li, nuclear thiab atomic physics. Tab sis cia peb saib ze dua ntawm cov tshuab. Cov ceg ntawm physics no cuam tshuam nrog kev kawm txog kev ua haujlwm ntawm lub cev. Nws tsim ib co qauv thiab kawm txog nws txoj kev.
Kinematics as part of mechanics
Cov tom kawg tau muab faib ua peb ntu: kinematics, dynamics thiab statics. Peb cov subsciences no, yog tias koj tuaj yeem hu rau lawv, muaj qee qhov tshwj xeeb. Piv txwv li, statics kawm cov kev cai rau qhov sib npaug ntawm cov tshuab tshuab. Ib qho kev koom tes nrog cov nplai tam sim los rau hauv siab. Dynamics kawm cov cai ntawm kev txav ntawm lub cev, tab sis tib lub sij hawm them nyiaj rau cov rog ua rau lawv. Tab sis kinematics ua tib yam, tsuas yog cov rog tsis suav nrog. Yog li ntawd, qhov loj ntawm tib lub cev tsis suav nrog hauv cov haujlwm.
Cov ntsiab lus tseem ceeb ntawm kinematics. Mechanical zog
Kev kawm hauv qhov kev tshawb fawb no yog cov ntsiab lus tseem ceeb. Nws yog to taub raws li ib tug lub cev, qhov luaj li cas ntawm uas, nyob rau hauv kev sib piv nrog ib tug tej yam mechanical system, yuav tsum neglected. Qhov no thiaj li hu ua lub cev zoo tagnrho yog zoo ib yam li cov roj zoo tagnrho, uas yog suav tias yog nyob rau hauv seem ntawm molecular physics. Feem ntau, lub tswv yim ntawm cov khoom taw tes, ob qho tib si hauv mechanics feem ntau thiab hauv kinematics tshwj xeeb, plays lub luag haujlwm tseem ceeb. Qhov feem ntau suav hais tias yog hu ua kev txhais lus txav.
txhais li cas thiab nws yuav ua li cas?
Feem ntau txav tau muab faib ua kev sib hloov thiab kev txhais lus. Cov ntsiab lus tseem ceeb ntawm kinematics ntawm kev txhais lus yog feem ntau cuam tshuam nrog cov khoom siv hauv cov qauv. Peb yuav tham txog lawv tom qab, tab sis tam sim no cia peb rov qab mus rau hom kev txav mus los. Nws yog tseeb hais tias yog hais tias peb tham txog rotational, ces lub cev yog spinning. Raws li, kev txhais lus txav yuav raug hu ua kev txav ntawm lub cev hauv lub dav hlau lossis linearly.
Theoretical hauv paus rau kev daws teeb meem
Kinematics, cov ntsiab lus tseem ceeb thiab cov qauv uas peb tab tom xav txog tam sim no, muaj ntau txoj haujlwm. Qhov no yog ua tiav los ntawm cov niaj hnub combinatorics. Ib txoj hauv kev ntawm kev sib txawv ntawm no yog hloov cov xwm txheej tsis paub. Ib qho thiab tib qhov teeb meem tuaj yeem nthuav tawm hauv lub teeb sib txawv los ntawm kev hloov lub hom phiaj ntawm nws txoj kev daws teeb meem. Nws yuav tsum nrhiav kev deb, ceev, sijhawm, acceleration. Raws li koj tuaj yeem pom, muaj ntau ntau txoj kev xaiv. Yog tias peb suav nrog cov xwm txheej ntawm lub caij nplooj zeeg dawb ntawm no, qhov chaw yuav yooj yim unimaginable.
Tus nqi thiab cov qauv
Ua ntej tshaj, cia peb ua ib qho kev tshwj tseg. Raws li paub, qhov ntau tuaj yeem muaj qhov xwm txheej dual. Ntawm qhov tod tes, qee tus lej muaj txiaj ntsig yuav sib raug rau qee tus nqi. Tab sis ntawm qhov tod tes, nws kuj tuaj yeem muaj kev taw qhia ntawm kev faib khoom. Piv txwv li, nthwv dej. Hauv optics, peb tau ntsib nrog lub tswv yim xws li wavelength. Tab sis yog hais tias muaj ib coherent teeb qhov chaw (zoo tib yam laser), ces peb tab tom soj ntsuam nrog ib tug beam ntawm dav hlau polarized nthwv dej. Yog li, nthwv dej yuav sib raug zoo tsis yog rau tus lej tus nqi qhia nws qhov ntev, tab sis kuj rau ib qho kev qhia ntawm kev nthuav tawm.
Classic piv txwv
Cov xwm txheej zoo li no yog qhov piv txwv ntawm kev siv tshuab. Cia peb hais tias lub laub tab tom dov pem hauv ntej ntawm peb. Los ntawmqhov xwm ntawm lub zog, peb tuaj yeem txiav txim siab vector yam ntxwv ntawm nws qhov nrawm thiab nrawm. Nws yuav nyuaj me ntsis ua qhov no thaum tsiv mus rau pem hauv ntej (piv txwv li hauv pem teb tiaj tus), yog li peb yuav xav txog ob qhov xwm txheej: thaum lub laub dov thiab thaum nws dov.
Cia li xav tias lub laub yuav nce me ntsis. Nyob rau hauv rooj plaub no, nws yuav qeeb yog tias tsis muaj zog sab nraud ua rau nws. Tab sis nyob rau hauv qhov teeb meem rov qab, uas yog, thaum lub laub dov, nws yuav ceev. Qhov ceev hauv ob qhov xwm txheej yog coj mus rau qhov chaw uas cov khoom txav mus. Qhov no yuav tsum tau ua raws li txoj cai. Tab sis acceleration tuaj yeem hloov vector. Thaum decelerating, nws yog qhia nyob rau hauv cov kev taw qhia opposite mus rau lub velocity vector. Qhov no piav qhia txog kev qeeb qeeb. Cov saw hlau zoo sib xws tuaj yeem siv rau qhov xwm txheej thib ob.
Lwm tus nqi
Peb nyuam qhuav tham txog qhov tseeb tias hauv kinematics lawv ua haujlwm tsis yog nrog cov lej ntau, tab sis kuj nrog vectors. Tam sim no cia peb ua nws ib kauj ruam ntxiv. Ntxiv rau qhov nrawm thiab nrawm, thaum daws teeb meem, cov yam ntxwv xws li kev ncua deb thiab lub sijhawm siv. Los ntawm txoj kev, qhov ceev tau muab faib ua thawj zaug thiab instantaneous. Thawj ntawm lawv yog qhov tshwj xeeb ntawm qhov thib ob. Instantaneous ceev yog qhov ceev uas tuaj yeem nrhiav tau ntawm txhua lub sijhawm. Thiab nrog thawj zaug, tej zaum, txhua yam yog qhov tseeb.
Task
Ib feem ntau ntawm txoj kev xav tau kawm los ntawm peb ua ntej hauv kab lus dhau los. Tam sim no nws tseem tsuas yog muab cov qauv yooj yim. Tab sis peb yuav ua tau txawm tias zoo dua: Peb yuav tsis tsuas yog xav txog cov qauv, tab sis kuj siv tau thaum daws cov teeb meem hauv kev txiav txim siabua kom tiav qhov kev paub tau. Kinematics siv tag nrho cov qauv, sib txuas uas, koj tuaj yeem ua tiav txhua yam koj xav tau los daws. Nov yog ib qho teeb meem nrog ob yam xwm txheej kom nkag siab qhov no tag nrho.
Tus neeg caij tsheb kauj vab qeeb tom qab hla txoj kab tiav. Nws coj nws tsib vib nas this los ua kom tiav. Nrhiav kom paub seb nws nrawm nrawm npaum li cas, nrog rau ntau npaum li cas braking nrug nws tswj kom npog. Lub braking nrug yog suav hais tias yog linear, qhov kawg ceev yog muab sib npaug rau xoom. Thaum lub sijhawm hla txoj kab tiav, qhov ceev yog 4 meters ib ob.
Qhov tseeb, txoj haujlwm yog qhov nthuav heev thiab tsis yooj yim li nws yuav zoo li thaum xub thawj siab ib muag. Yog tias peb sim coj tus qauv nyob deb hauv kinematics (S=Vot + (-) (at ^ 2/2)), ces tsis muaj dab tsi los ntawm nws, vim peb yuav muaj qhov sib npaug nrog ob qhov sib txawv. Yuav ua li cas mus rau qhov xwm txheej zoo li no? Peb tuaj yeem mus ob txoj hauv kev: ua ntej xam qhov nrawm los ntawm kev hloov cov ntaub ntawv rau hauv cov mis V=Vo - ntawm, lossis nthuav tawm qhov nrawm los ntawm qhov ntawd thiab hloov nws mus rau hauv cov qauv kev ncua. Wb siv thawj txoj kev.
Yog li, qhov kawg tshaj tawm yog xoom. Pib - 4 meters ib ob. Los ntawm kev hloov cov khoom sib thooj mus rau sab laug thiab sab xis ntawm qhov sib npaug, peb ua tiav cov lus qhia rau kev nrawm. Nov yog: a=Vo/t. Yog li, nws yuav muab sib npaug rau 0.8 meters ib ob squared thiab yuav muaj ib tug braking cim.
mus rau tus qauv kev ncua deb. Peb tsuas hloov cov ntaub ntawv rau hauv nws. Peb tau txais cov lus teb: qhov kev ncua deb yog 10 meters.
