Yog tias koj tau pom lwm lub tsheb nrawm dhau koj lub tsheb tom qab lub teeb liab, tom qab ntawd koj tau ntsib qhov sib txawv ntawm kev nrawm ua ntej. Kev nrawm yog tus nqi ntawm qhov khoom uas qhov nrawm hloov pauv thaum nws txav mus. Koj tuaj yeem suav qhov nrawm, nthuav tawm hauv meters ib pliag ib pliag, raws lub sijhawm nws siv lub hom phiaj los hloov nws qhov nrawm, lossis raws li lub zog ua rau ntawm qhov khoom.
Kauj ruam
Txoj Kev 1 ntawm 3: Xam Tawm Kev Ua Haujlwm nrawm los ntawm Force
Kauj Ruam 1. Nkag Siab Newton txoj cai thib ob ntawm kev txav chaw
Newton txoj cai lij choj thib ob hais tias thaum lub zog ua haujlwm ntawm ib yam khoom tsis sib xws, lub hom phiaj yuav nrawm dua. Qhov kev nrawm no yog txiav txim siab los ntawm qhov tshwm sim quab yuam ntawm qhov khoom, nrog rau qhov hnyav ntawm qhov khoom nws tus kheej. Kev nrawm tuaj yeem suav tau yog tias lub zog siv rau ntawm ib qho khoom thiab qhov hnyav ntawm cov khoom tau paub.
- Newton txoj cai tuaj yeem txhais ua kab zauv Fnqa = mx a, nrog Fnqa Qhia tawm cov txiaj ntsig tshwm sim ntawm qhov khoom, m qhov hnyav ntawm qhov khoom, thiab kev nrawm ntawm qhov khoom.
- Siv cov ntsuas ntsuas thaum siv qhov sib npaug no. Siv lub kilogram (kg) raws li chav tsev ntawm qhov hnyav, Newton (N) raws li chav tsev ntawm kev quab yuam, thiab meters ib ob npaug ob npaug (m/s)2) qhia kev nrawm.
Kauj Ruam 2. Txiav txim siab qhov hnyav ntawm qhov khoom
Txhawm rau paub qhov hnyav ntawm cov khoom, koj tuaj yeem ntsuas nws ntawm qhov sib npaug thiab sau nws qhov hnyav hauv grams. Yog tias yam khoom koj muaj yog qhov loj heev, koj yuav xav tau daim ntawv txheeb xyuas kom paub nws qhov hnyav. Cov khoom loj feem ntau muaj qhov hnyav hnyav (kg).
Koj yuav tsum hloov cov chav ntawm qhov hnyav mus rau kilograms kom txuas ntxiv nrog kev suav nrog qhov sib npaug no. Yog tias qhov hnyav ntawm koj cov khoom raug qhia hauv grams, koj tsuas yog yuav tsum faib tus nqi los ntawm 1000 kom hloov nws mus rau kilograms
Kauj Ruam 3. Xam qhov tshwm sim quab yuam ntawm qhov khoom
Qhov tshwm sim quab yuam yog lub zog tsis sib luag. Yog tias muaj ob lub zog uas sib tawm tsam rau ib leeg, thiab ib qho ntawm lawv loj dua lwm qhov, qhov tshwm sim ntawm ob lub zog yuav zoo ib yam li cov lus qhia ntawm lub zog loj dua. Kev nrawm nrawm tshwm sim thaum ib yam khoom paub txog lub zog tsis sib luag, yog li nws qhov nrawm hloov pauv mus rau qhov quab yuam uas rub lossis thawb nws.
- Piv txwv li: cia peb hais koj thiab koj tus muam ua si sib ntaus sib tua. Koj rub txoj hlua mus rau sab laug nrog lub zog ntawm 5 Newtons, thaum koj tus tij laug rub txoj hlua nyob rau sab nraud nrog lub zog ntawm 7 Newtons. Qhov tshwm sim quab yuam ntawm txoj hlua yog 2 Newtons rau sab laug, ntawm koj tus nus.
- Txhawm rau nkag siab cov chav nyob zoo dua, nkag siab tias 1 Newton (1 N) yog sib npaug rau 1 kilogram-meter/thib ob (kg-m/s)2).
Kauj Ruam 4. Hloov cov kab zauv F = ma los daws qhov teeb meem nrawm
Koj tuaj yeem hloov qhov kev txiav txim ntawm cov mis los laij nrawm, los ntawm kev faib ob sab ntawm qhov sib npaug los ntawm qhov hnyav, yog li koj tau txais qhov kev ua zauv: a = F/m. Txhawm rau nrhiav kev nrawm, koj tsuas yog yuav tsum faib lub zog los ntawm qhov hnyav ntawm cov khoom uas tau ntsib nws.
- Lub zog yog ncaj qha sib npaug rau kev nrawm, uas txhais tau tias, ntau dua qhov kev quab yuam tau ntsib los ntawm ib yam khoom, kev nrawm yuav ntau dua.
- Pawg yog qhov sib npaug sib npaug rau kev nrawm, uas txhais tau tias, qhov hnyav ntau dua ib yam khoom muaj, qhov tsawg dua nws yuav muaj.
Kauj Ruam 5. Siv cov mis los daws qhov teeb meem nrawm
Kev nrawm yog sib npaug rau qhov tshwm sim quab yuam ntawm ib qho khoom faib los ntawm nws qhov hnyav. Thaum koj tau sau qhov paub sib txawv, ua qhov faib kom pom cov khoom nrawm dua.
- Piv txwv li: lub zog ntawm 10 Newtons tau ua rau tib txoj kev coj ntawm cov khoom hnyav 2 kg. Dab tsi yog qhov nrawm?
- a = F/m = 10/2 = 5 m/s2
Txoj Kev 2 ntawm 3: Xam Qhov Nruab Nrab Kev Ua Haujlwm ntawm Ob Qhov Ceev
Kauj Ruam 1. Txiav txim siab qhov sib npaug rau qhov nrawm nrawm
Koj tuaj yeem suav qhov nruab nrab nrawm ntawm cov khoom dhau ntawm qee lub sijhawm ntawm nws raws li nws qhov nrawm (qhov nrawm ntawm qhov khoom hauv qee qhov kev qhia), ua ntej thiab tom qab lub sijhawm ntawd. Txhawm rau xam nws, koj yuav tsum paub qhov sib npaug rau laij nrawm: ib = v / t qhov twg sawv cev rau kev nrawm, v qhov hloov pauv hauv qhov nrawm, thiab t lub sijhawm nws yuav siv los hloov qhov khoom nrawm.
- Chav tsev ntawm kev nrawm yog meters ib pliag thib ob, lossis m/s2.
- Kev nrawm yog qhov muaj nuj nqis vector, uas txhais tau tias nws muaj ob qho loj thiab qhov taw qhia. Qhov nrawm ntawm qhov nrawm yog tag nrho cov nyiaj, thaum nws txoj kev taw qhia tau txiav txim siab los ntawm cov lus qhia uas cov khoom txav mus. Yog tias qhov khoom ua kom qeeb, qhov nrawm yuav tsis zoo.
Kauj Ruam 2. Nkag siab txog qhov hloov pauv
Koj tuaj yeem txiav txim siab v thiab t los ntawm kev suav ntxiv: v = vf -vkuv thiab t = tf - tkuv nrog vf sawv cev rau qhov tshaj tawm zaum kawg, vkuv thawj zaug ceev, tf lub sijhawm kawg, thiab tkuv thawj lub sij hawm
- Txij li kev nrawm nrawm muaj kev taw qhia, koj yuav tsum ib txwm txo qhov nrawm nrawm mus rau qhov pib tshaj tawm. Yog tias koj thim rov qab nws, qhov kev taw qhia ntawm kev nrawm koj tau txais yuav tsis raug.
- Tshwj tsis yog muaj lwm yam hais hauv qhov teeb meem, thawj lub sijhawm cov khoom txav feem ntau yog 0 vib nas this.
Kauj Ruam 3. Siv cov mis los nrhiav kev nrawm
Ua ntej tshaj, sau koj qhov kev ua zauv nrog rau txhua qhov paub sib txawv. Qhov sib npaug yog a = v / t = (vf -vkuv)/(t ibf - tkuv). Rho tawm qhov nrawm kawg los ntawm qhov pib nrawm, tom qab ntawd faib cov txiaj ntsig los ntawm lub sijhawm. Qhov tshwm sim yog qhov kwv yees qhov nruab nrab nrawm dua lub sijhawm ntawd.
- Yog tias qhov khoom qhov nrawm tshaj yog tsawg dua nws qhov kev tshaj tawm thawj zaug, qhov nrawm yuav tsis zoo, txhais tau tias lub hom phiaj yog qeeb qeeb.
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Piv txwv 1: kev sib tw tsheb sib tw nrawm tas li los ntawm 18.5 m/s txog 46.1 m/s hauv 2.47 vib nas this. Qhov nruab nrab nrawm yog dab tsi?
- Sau qhov sib npaug: a = v / t = (vf -vkuv)/(t ibf - tkuv)
- Sau cov kev paub sib txawv: vf = 46, 1 m/s, vkuv = 18.5 m/s, tf = 2,47s, tkuv = 0 tsi.
- Daws qhov sib npaug: a = (46, 1 - 18, 5)/2, 47 = 11, 17 meters/thib ob2.
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Piv txwv 2: tus neeg caij tsheb kauj vab nres ntawm 22.4 m/s tom qab 2.55 vib nas this ntawm nias tus nres. Txiav txim qhov ua kom qeeb.
- Sau qhov sib npaug: a = v / t = (vf -vkuv)/(t ibf - tkuv)
- Sau cov kev paub sib txawv: vf = 0 m/s, vkuv = 22.4 m/s, tauf = 2,55s, tkuv = 0 tsi.
- Daws qhov sib npaug: a = (0 -22, 4)/2, 55 = -8, 78 meters/thib ob2.
Txoj Kev 3 ntawm 3: Txheeb Xyuas Cov Lus Teb
Kauj Ruam 1. Kev taw qhia ntawm kev nrawm
Lub tswv yim ntawm kev nrawm hauv physics tsis yog ib txwm zoo ib yam uas tau siv hauv lub neej txhua hnub. Txhua qhov nrawm muaj qhov taw qhia, feem ntau qhia los ntawm lub cim zoo yog tias nws nce mus lossis mus rau sab xis, lossis tsis zoo yog tias nws tau nqes los yog sab laug. Txheeb ob zaug yog tias koj cov lus teb muaj txiaj ntsig raws li cov lus qhia hauv qab no:
| Tsheb Tsiv | Tsheb Hloov | Kev Ceev Ceev |
|---|---|---|
| Tsiv mus rau sab xis (+) nias lub roj tsheb | + → ++ (nrawm dua) | zoo |
| Txav mus sab xis (+) nias nres | ++ → + (tsis zoo) | tsis zoo |
| Txav mus rau sab laug (-) nias lub roj tsheb | - → - (ntau qhov tsis zoo) | tsis zoo |
| Tsiv sab laug (-) nias nres | - → - (tsawg dua qhov tsis zoo) | zoo |
| Tsiv ntawm qhov nrawm | tseem zoo li qub | acceleration yog xoom |
Kauj Ruam 2. Kev coj
Nco ntsoov, lub zog tsuas yog ua rau nrawm "nyob rau hauv cov lus qhia ntawm lub zog". Qee cov lus nug yuav dag koj nrog cov qhab nia uas tsis cuam tshuam nrog kev nrawm.
- Piv txwv teeb meem: cov khoom ua si nkoj nrog qhov hnyav ntawm 10 kg tau txav nrog kev nrawm mus rau sab qaum teb ntawm 2 m/s2. Cua tshuab lub nkoj sab hnub poob nrog lub zog ntawm 100 Newtons. Lub nkoj ceev mus rau sab qaum teb tom qab tau cua los cua li cas?
- Teb: vim tias qhov kev taw qhia ntawm qhov quab yuam yog nyob ib puag ncig rau qhov txav ntawm qhov khoom, nws tsis muaj kev cuam tshuam rau cov khoom txav mus rau qhov ntawd. Lub nkoj tseem yuav txav mus rau sab qaum teb nrog kev nrawm ntawm 2 m/s2.
Kauj Ruam 3. Cov txiaj ntsig zoo
Yog tias lub zog tau ntsib los ntawm ib yam khoom ntau dua ib qho, suav qhov tshwm sim quab yuam los ntawm txhua tus ntawm lawv ua ntej suav qhov nrawm. Nram qab no yog ib qho piv txwv rau teeb meem style ob sab:
- Piv txwv teeb meem: Lub Plaub Hlis tab tom rub lub thawv 400 kg rau sab laug nrog lub zog ntawm 150 Newtons. Bob sawv ntawm sab laug ntawm lub thawv thiab thawb nrog lub zog ntawm 200 Newtons. Cov cua tab tom tshuab rau sab laug nrog lub zog ntawm 10 Newtons. Dab tsi yog qhov nrawm ntawm lub thawv?
- Teb: cov lus nug saum toj no muab cov ntsiab lus nyuaj los dag koj. Kos daim duab thiab koj yuav pom lub zog ntawm 150 Newtons rau sab xis, 200 Newtons mus rau sab laug, thiab 10 Newtons mus rau sab laug. Yog tias "sab laug" yog qhov zoo, qhov tshwm sim quab yuam ntawm qhov khoom yog 150 + 200 - 10 = 340 Newtons. Kev nrawm ntawm cov khoom = F / m = 340 Newton / 400 kg = 0.85 m / s2.
