Kev nrawm yog kev suav ntawm qhov nrawm nrawm ntawm ib yam twg. Yog tias koj tau saib ntawm lub ntsuas hluav taws xob ntawm lub tsheb uas txav mus los, koj yuav pom qhov suav suav nrawm dua - rab koob txav mus deb dua, lub tsheb ceev dua. Muaj ntau txoj hauv kev los laij nrawm, nyob ntawm seb hom ntaub ntawv koj muaj. Feem ntau, cov mis ceev = nrug/sijhawm (lossis k = j/w) yog txoj hauv kev yooj yim tshaj plaws los suav qhov nrawm.
Kauj ruam
Txoj Kev 1 ntawm 3: Siv Cov Qauv Ntsuas Tus Qauv Ceev
Kauj Ruam 1. Nrhiav qhov nrug qhov khoom uas tau mus lawm
Cov mis yooj yim uas neeg feem coob siv los nrhiav qhov nrawm ntawm qee yam yog yooj yim heev rau siv. Ua ntej tshaj plaws, koj yuav tsum paub "nrug deb npaum li cas cov khoom ntsuas tau mus ncig". Hauv lwm lo lus, qhov kev ncua deb ntawm qhov pib thiab qhov kawg ntawm qhov khoom yog dab tsi?
Cov mis no yooj yim to taub los ntawm qhov piv txwv. Cia peb hais tias peb taug kev los ntawm tsheb mus rau chaw ua si rau "161 kilometers". Hauv ob peb kauj ruam, peb tuaj yeem siv cov ntaub ntawv no los ua kom tiav cov lej ntawm cov mis
Kauj Ruam 2. Nrhiav lub sijhawm nws yuav siv lub hom phiaj mus rau qhov deb ntawd
Cov ntaub ntawv tom ntej koj xav tau yog ntev npaum li cas nws thiaj siv lub hom phiaj kom mus txog qhov deb. Hauv lwm lo lus, nws siv sijhawm ntev npaum li cas rau qhov khoom txav los ntawm qhov pib mus rau qhov kawg?
Hauv qhov piv txwv no, cia peb hais qhov khoom siv kwv yees kwv yees. ob teev kom tau mus rau lub hom phiaj.
Kauj Ruam 3. Faib qhov nrug deb ntawm lub sijhawm siv los nrhiav cov khoom nrawm
Koj tsuas xav tau ob daim ntawv ntawm cov ntaub ntawv kom paub qhov nrawm ntawm qhov khoom. Qhov kev ncua deb mus rau lub sijhawm yog sib npaug ntawm cov khoom nrawm.
Hauv qhov piv txwv no, 161 kilometers/2 teev = 80.5 km/teev.
Kauj Ruam 4. Tsis txhob hnov qab chav tsev siv
Nws yog ib qho tseem ceeb heev uas yuav tsum tau siv cov chav nyob hauv koj cov lus teb (xws li kilometers ib teev, thiab lwm yam) Tsis muaj cov koog no, nws nyuaj rau tib neeg nkag siab lub ntsiab lus ntawm koj cov lus teb. Koj tseem tuaj yeem poob cov ntsiab lus yog tias koj siv chav tsis raug thaum ua haujlwm hauv tsev kawm ntawv.
Chav tsev ceev yog chav nyob nrug deb rau lub sijhawm. Piv txwv li, txij li peb ntsuas kev nrug deb hauv kilometers thiab sijhawm nyob rau teev, cov koog siv tau yog km/teev (los yog kilometers ib teev).
Txoj Kev 2 ntawm 3: Daws Teeb Meem Nyuaj Tshaj
Kauj Ruam 1. Nrhiav ob peb yam sib txawv los daws qhov teeb meem ntawm qhov deb thiab sijhawm
Thaum koj nkag siab cov qauv yooj yim rau kev nrawm, koj tuaj yeem siv nws los ua cov lus teb uas tsis yog nrawm. Piv txwv li, yog tias thaum xub thawj koj tsuas paub qhov nrawm ntawm qhov khoom thiab lwm qhov sib txawv, koj tuaj yeem kho cov qauv saum toj no kom pom cov ntaub ntawv tsis paub.
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Piv txwv li, cia peb hais tias peb paub tias lub tsheb ciav hlau taug kev ntawm 20 kilometers ib teev twg rau plaub teev, tab sis peb tsis paub tias nws tau mus deb npaum li cas. Txhawm rau paub, peb tuaj yeem rov kho cov mis raws li hauv qab no:
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- ceev = nrug/sijhawm
- sijhawm × sijhawm = (nrug/sijhawm) × sijhawm
- ceev × sijhawm = nrug
- 20 km/teev × 4 teev = nrug = 80km ua
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Kauj Ruam 2. Hloov cov koog koj siv raws li xav tau
Qee zaum, koj yuav xam nrawm siv chav tsev tshwj xeeb, tab sis xav tau hloov nws mus rau lwm chav. Hauv qhov no, koj yuav tsum siv qhov hloov pauv hloov kom tau txais cov lus teb raws li chav nyob raug. Txhawm rau ua qhov no, tsuas yog sau qhov kev sib raug zoo ntawm cov koog nyob hauv daim ntawv fraction thiab sib npaug. Thaum muab sib dhos, thim rov qab cov feem raws li xav tau kom tshem tawm cov chav tsis xav tau. Txoj kev no yooj yim dua li nws lub suab!
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Piv txwv li, cia peb hais tias hauv qhov piv txwv teeb meem saum toj no, peb xav tau cov lus teb hauv mais tsis yog kilometers. Ib mais sib npaug li 1.6 kilometers. Yog li, peb tuaj yeem hloov pauv raws li hauv qab no:
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- 80 kilometers × 1 mais/1.6 kilometers = 50 miv
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- Nco ntsoov, vim hais tias cov kilometers pom nyob rau hauv qab ntawm cov feem, nws tshem tawm cov kilometers los ntawm cov lus teb yav dhau los, yog li qhov txiaj ntsig kawg siv mais.
- Lub vev xaib no muab cov kev hloov pauv rau feem ntau ntawm cov koog siv feem ntau.
Kauj Ruam 3. Hloov qhov "nrug deb" sib txawv nrog cov lej nrug raws li xav tau
Cov khoom tsis tas yuav txav mus ncaj, txoj kev du. Yog tias qhov no muaj tseeb, koj yuav tsis tuaj yeem nkag mus rau tus lej tus lej raws li chav nyob nrug deb rau hauv tus qauv tus lej nrawm. Txawm li cas los xij, koj yuav xav hloov tsab ntawv j hauv cov qauv k = j/w nrog cov qauv uas zoo ib yam li qhov kev mus los ntawm lub hom phiaj.
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Piv txwv li, cia peb hais tias lub dav hlau tig los ntawm huab cua nyob deb li ntawm 20 mais 5 zaug. Lub dav hlau ua tiav qhov puag ncig hauv ib nrab teev. Hauv qhov piv txwv no, peb tseem yuav tsum nrhiav qhov nrug deb uas ya los ntawm lub dav hlau ua ntej peb tuaj yeem txiav txim siab nws qhov nrawm. Peb tuaj yeem siv cov mis rau xam qhov deb ib ncig ntawm lub voj voog (nrug ib puag ncig nws) tsis txhob siv j hauv cov mis no. Cov mis no yog ib puag ncig = 2πr qhov twg r = radius ntawm lub voj voog. Nov yog yuav daws nws li cas:
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- k = (2 × × r)/w
- k = (2 × × 10) /0.5
- k = 62.83/0.5 = 125.66 mais/teev
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Kauj Ruam 4. Nkag siab tias k = j/w muab qhov nruab nrab nrawm
Cov mis yooj yim thiab yooj yim peb siv los nrhiav qhov nrawm muaj ib qhov tsis zoo. Qhov txiaj ntsig tshwm sim yog thev naus laus zis nruab nrab nrawm. Qhov no txhais tau tias cov mis xav tias cov khoom koj tab tom ntsuas siv qhov nrawm ib yam thaum nws txav mus. Raws li peb yuav pom hauv qab no, nrhiav qhov nrawm ntawm ib yam khoom hauv ib pliag yuav nyuaj dua.
Txhawm rau qhia qhov sib txawv no, xav txog zaum kawg uas koj tau caij tsheb. Nws tsis zoo li koj yuav tau taug kev nrawm ib yam li koj tab tom taug kev. Txawm li cas los xij, koj feem ntau yuav pib koj txoj kev taug ntawm qhov nrawm thiab maj mam nce koj txoj kev nrawm, nres vim yog teeb liab, tsheb sib tsoo, thiab lwm yam. Yog tias koj siv tus qauv ntsuas tus lej kom pom nrawm thaum mus ncig, kev hloov pauv rau qhov nrawm ntawd tsis tuaj yeem kuaj pom. Txawm li cas los xij, koj yuav tau txais cov lus teb uas qhia qhov nrawm nruab nrab ntawm txhua qhov kev sib txawv nrawm uas koj mus
Txoj Kev 3 ntawm 3: Xam Tawm Ceev
Nco tseg:
Nqe lus no siv cov txuj ci uas tsis paub ntau rau cov neeg uas tsis tau kawm txog kev suav lej. Nyeem peb kab lus ntawm kev laij lej kom pab tau.
Kauj Ruam 1. Nkag siab tias qhov nrawm tau txhais raws li qhov nrawm
Kev suav suav nrawm nrawm tau nkag siab heev vim cov lej thiab cov kws tshawb fawb siv cov ntsiab lus sib txawv los piav qhia "nrawm" thiab "nrawm". Kev nrawm muaj ob ntu: "tus nqi" thiab "kev taw qhia". Tus nqi sib npaug rau qhov khoom nrawm. Kev hloov pauv hauv qhov kev taw qhia yuav ua rau muaj kev hloov pauv nrawm, tab sis tsis yog hloov pauv nrawm.
- Piv txwv li, cia peb hais tias ob lub tsheb tau txav mus rau lwm qhov. Tus ntsuas ntsuas nrawm ntawm ob lub tsheb tso saib daim duab ntawm 50 km/h yog li lawv ob leeg tau taug kev ntawm tib lub nrawm. Txawm li cas los xij, txij li cov tsheb tau txav deb ntawm ib leeg, peb tuaj yeem hais tias ib lub tsheb muaj "nrawm" ntawm -50 km/h thaum lwm tus muaj "nrawm" ntawm 50 km/h.
- Ib yam li kev suav nrawm nrawm, koj tseem tuaj yeem ua qhov kev suav nrawm nrawm.
Kauj Ruam 2. Siv qhov tseem ceeb los ntsuas qhov ua kom tsis zoo
Ib yam khoom tuaj yeem muaj qhov tsis zoo ntawm kev nrawm (yog tias nws txav mus rau qhov tsis zoo piv rau lwm yam khoom). Txawm li cas los xij, tsis muaj qhov nrawm nrawm. Yog li, hauv qhov no, qhov muaj txiaj ntsig ntawm tus nqi qhia txog qhov khoom nrawm.
Vim li no, hauv qhov piv txwv teeb meem saum toj no, ob lub tsheb muaj kev nrawm dua 50 km/teev.
Kauj Ruam 3. Siv qhov sib piv ntawm txoj haujlwm ntawm txoj haujlwm
Yog tias koj muaj lub luag haujlwm k (w) uas qhia txog txoj haujlwm ntawm ib yam khoom yam tsis xav tau los xam lub sijhawm, qhov txiaj ntsig ntawm k (w) yuav qhia qhov nrawm dua yam tsis xav tau sijhawm. Tsuas yog ntsaws lub sijhawm tus nqi rau hauv cov mis no kom qhov sib txawv w (lossis lub sijhawm twg los xij tus nqi tau siv) tau nrawm dua raws li lub sijhawm ntawd. Los ntawm no, koj tuaj yeem yooj yim pom cov khoom nrawm.
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Piv txwv, cia peb hais tias txoj haujlwm ntawm ib qho khoom hauv ib lub 'meter' tau piav qhia hauv qhov sib npaug 3q2 + w - 4 qhov twg w = sijhawm hauv vib nas this. Peb xav paub qhov khoom nrawm ntawm w = 4 vib nas this. Hauv qhov no, koj tuaj yeem daws nws los ntawm:
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- 3w xav2 +wb - 4
- k '(w) = 2 × 3w + 1
- k '(w) = 6w + 1
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Tam sim no, peb sau w = 4:
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- k '(w) = 6 (4) + 1 = 24 + 1 = 25 meters/thib ob. Txuj ci qhov no yog kev suav ntawm kev nrawm, tab sis txij li nws tau zoo thiab cov lus qhia tsis tau hais hauv nqe lus nug, peb tuaj yeem siv nws los nrhiav qhov nrawm.
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Kauj Ruam 4. Siv qhov ua kom nrawm nrawm
Kev nrawm yog ib txoj hauv kev ntsuas qhov kev hloov pauv ntawm qhov khoom ntawm lub sijhawm dhau los. Cov ncauj lus no nyuaj dhau los piav qhia tag nrho hauv kab lus no. Txawm li cas los xij, nws muaj txiaj ntsig zoo kom nco ntsoov tias thaum koj muaj lub luag haujlwm a (w) uas sawv cev rau kev nrawm nrog kev hwm rau lub sijhawm, qhov tseem ceeb ntawm a (w) yuav rov qab los ntawm kev nrawm raws li lub sijhawm ntawd. Nco ntsoov, nws muaj txiaj ntsig zoo kom paub qhov pib nrawm ntawm cov khoom kom koj tuaj yeem txheeb xyuas qhov tas li ntawm qhov tshwm sim los ntawm qhov tsis muaj qhov sib xws.
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Piv txwv, cia peb hais tias cov khoom muaj qhov nrawm nrawm (hauv m/s2 raws li qhov tshwm sim ntawm a (w) = -30. Kuj hais tias cov khoom muaj qhov pib nrawm ntawm 10 m/s. Peb yuav tsum nrhiav qhov nrawm ntawm w = 12 vib nas this. Hauv qhov no, peb tuaj yeem daws nws los ntawm:
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- a (w) = -30
- p (w) = a (w) dw = -30dw = -30w + C
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Txhawm rau nrhiav C, peb yuav daws p (w) rau w = 0. Nco ntsoov tias lub hom phiaj qhov pib nrawm yog 10 m/s.
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- p (0) = 10 = -30 (0) + C
- 10 = C, yog li p (w) = -30w + 10
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Tam sim no, peb tuaj yeem nkag mus w = 12 vib nas this.
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- p (12) = -30 (12) + 10 = -360 + 10 = -350. Txij li qhov tshaj tawm yog qhov muaj txiaj ntsig ntawm kev nrawm, lub hom phiaj tshaj tawm yog 350 meters/thib ob.
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Lub tswv yim
- Kev xyaum ua kom zoo! Sim tsim koj tus kheej cov lus nug los ntawm kev hloov tus lej hauv qhov piv txwv teeb meem saum toj no.
- Yog tias koj tab tom nrhiav txoj hauv kev nrawm los xyaum ua lej kom zoo dua kev suav, siv lub tshuab laij lej online los ntawm no thiab lub laij lej suav nrog online ntawm no.
