Tsab xov xwm hais txog Qhov ntau ntawm physics hauv kev txav mus los linear
1. Lub sijhawm luv
Thaum ib yam khoom txav ntawm ib qho chaw mus rau lwm qhov, yam khoom xav tau lub sijhawm luv luv. Lub cim sijhawm yog t (lub sijhawm). Lub tshuab ntsuas sijhawm thoob ntiaj teb yog thib ob (s).
2. Qhov nrug thiab kev hloov chaw
Qhov deb yog qhov ntev ntawm txoj kev uas ib yam khoom taug. Qhov deb yog ib qho scalar quantity, qhov twg qhov ntau tsis nyob ntawm kev coj. Lub cim qhov deb yog d thiab lub tshuab ntsuas thoob ntiaj teb yog ib 'meter' (m).
Kev Hloov Chaw yog kev hloov pauv ntawm qhov chaw ntawm ib yam khoom. Kev hloov chaw yog cov vector ntau npaum li cas, yog li kev hloov chaw muaj qhov loj ntawm kev hloov chaw thiab kev coj ntawm kev hloov chaw. Kev hloov chaw nyob ntawm kev coj kom nws tuaj yeem yog qhov zoo lossis tsis zoo. Yog tias nws raug suav hauv Cartesian coordinates ces raws li qhov kev pom zoo, yog tias kev coj ntawm kev hloov chaw yog nyob rau hauv kev coj ntawm x-axis zoo thiab y-axis zoo, ces kev hloov chaw yog qhov zoo. Ntawm qhov tsis sib xws, yog tias kev coj ntawm kev hloov chaw yog nyob rau hauv kev coj ntawm x-axis tsis zoo thiab y-axis tsis zoo ces kev hloov chaw yog qhov tsis zoo. Kev coj ntawm kev hloov chaw kuj feem ntau hais nyob rau sab qaum teb, sab hnub tuaj, sab qab teb, sab hnub poob. Lub cim ntawm kev hloov chaw yog d thiab lub tshuab thoob ntiaj teb yog ib 'meter' (m).
Piv txwv teeb meem 1:
Ib tug tub ntxhais kawm txav mus rau sab hnub tuaj mus txog 2 meters. Qhov deb thiab qhov loj ntawm qhov kev hloov chaw ntawm tus tub ntxhais kawm yog dab tsi?
a = qhov chaw pib, b = qhov chaw kawg.
Qhov Nrug Deb (d) = 2 m
Qhov loj ntawm kev hloov chaw (d) = 2 m. Kev taw qhia ntawm kev hloov chaw = sab hnub tuaj
Piv txwv teeb meem 2:
Ib tug tub ntxhais kawm txav mus rau sab hnub tuaj mus txog 2 meters thiab tom qab ntawd txav mus rau sab hnub poob mus txog 2 meters. Qhov deb thiab qhov loj ntawm qhov kev hloov chaw ntawm tus tub ntxhais kawm yog dab tsi?
a = qhov chaw pib thiab qhov chaw kawg
Qhov Nrug Deb (d) = 2 m + 2 m = 4 m
Qhov loj ntawm kev hloov chaw (d) = 2 m – 2 m = 0. Qhov chaw kawg = qhov chaw pib kom tsis muaj kev hloov chaw.
Piv txwv teeb meem 3:
Ib tug tub ntxhais kawm txav mus rau sab hnub tuaj mus txog 2 meters thiab tom qab ntawd txav mus rau sab hnub poob mus txog 1 meters. Qhov deb thiab qhov loj ntawm qhov kev hloov chaw ntawm tus tub ntxhais kawm yog dab tsi?
a = qhov chaw pib, b = qhov chaw xaus.
Qhov Nrug Deb (d) = 2 m + 1 m = 3 m
Qhov loj ntawm kev hloov chaw (d) = 2 m – 1 m = 1 m. Kev taw qhia ntawm kev hloov chaw = sab hnub tuaj
3. Kev ceev thiab qhov ceev
Qhov ceev yog qhov ntau scalar, thaum qhov ceev yog qhov ntau vector. Qhov ceev muaj qhov loj ntawm qhov ceev thiab kev coj ntawm qhov ceev. Lub cim ntawm qhov ceev yog v thiab lub cim ntawm qhov ceev yog v (qhov ceev). Lub tshuab thoob ntiaj teb ntawm qhov ceev thiab qhov ceev yog meters ib ob (m/s).
a. Qhov nruab nrab ntawm qhov ceev thiab qhov nruab nrab ntawm qhov ceev
Piv txwv teeb meem 1:
Ib tug tub ntxhais kawm txav mus rau sab hnub tuaj mus txog 2 meters rau 1 vib nas this. Qhov nruab nrab ntawm qhov ceev thiab qhov loj ntawm qhov nruab nrab ntawm tus tub ntxhais kawm yog dab tsi?
Qhov kev taw qhia ntawm qhov nruab nrab ntawm qhov ceev = qhov kev taw qhia ntawm kev hloov chaw = mus rau sab hnub tuaj
Piv txwv teeb meem 2:
Ib tug tub ntxhais kawm ntawv txav mus rau sab hnub tuaj mus txog 2 meters rau 1 vib nas this thiab tom qab ntawd txav mus rau sab hnub poob mus txog 1 meters rau 2 vib nas this. Qhov nruab nrab ntawm qhov ceev thiab qhov loj ntawm qhov nruab nrab ntawm tus tub ntxhais kawm ntawv yog dab tsi?
Kev taw qhia ntawm qhov nruab nrab ntawm qhov ceev = kev taw qhia ntawm kev hloov chaw = mus rau sab hnub tuaj
b. Qhov ceev tam sim ntawd thiab qhov ceev tam sim ntawd
Qhov ceev tam sim ntawd = qhov deb me me uas tau mus ncig hauv lub sijhawm luv luv. Qhov loj ntawm qhov ceev tam sim ntawd = qhov kev hloov pauv me me uas tau mus ncig hauv lub sijhawm luv luv. Yog tias koj tau caij maus taus lossis tsheb, koj yeej tau pom lub speedometer. Thaum caij maus taus, qhov ceev ntawm maus taus hloov pauv thiab qhia los ntawm lub speedometer.
Hauv kev kawm txog physics, qhov ceev tam sim ntawd feem ntau raug luv ua qhov ceev. Ib yam li ntawd, qhov ceev tam sim ntawd feem ntau raug luv ua qhov ceev. Thov nco ntsoov tias peb tuaj yeem hloov qhov loj ntawm qhov ceev nrog qhov ceev. Qhov no yog vim qhov loj ntawm qhov ceev raug suav hais tias sib npaug rau qhov ceev. Qhov loj ntawm qhov ceev raug suav hais tias sib npaug rau qhov ceev vim tias qhov deb thiab qhov loj ntawm kev hloov chaw yog tib yam yog tias nws me heev. Txawm hais tias qhov deb thiab qhov loj ntawm kev hloov chaw tsis zoo ib yam (piv nrog kev sib tham txog qhov deb thiab kev hloov chaw), tab sis yog tias qhov deb thiab qhov loj ntawm kev hloov chaw me heev ces lawv yuav tsum muaj tib tus nqi.
4. Kev nrawm dua
Kev nrawm yog ib qho vector ntau yog li ntawd muaj qhov loj ntawm kev nrawm thiab kev coj ntawm kev nrawm. Lub cim ntawm kev nrawm yog a (kev nrawm). Chav SI ntawm kev nrawm yog meters ib ob squared (m/s 2 ).
a. Kev nrawm nruab nrab
Qauv teeb meem:
Ib lub tsheb pib mus rau sab hnub tuaj ntawm qhov chaw nres kom txog thaum nws mus txog qhov ceev ntawm 10 m/s rau 5 vib nas this. Xam qhov loj ntawm qhov nruab nrab ntawm qhov kev nrawm!
Qhov kev taw qhia ntawm qhov nruab nrab acceleration yog mus rau sab hnub tuaj.
Qhov nruab nrab, qhov ceev ntawm lub tsheb nce 2 m/s txhua ob. Yog tias qhov loj ntawm qhov kev nrawm ntawm lub tsheb tsis hloov pauv ces qhov ceev ntawm lub tsheb yeej ib txwm nce 2 m/s txhua ob. Yog tias qhov loj ntawm qhov kev nrawm ntawm lub tsheb tsis hloov pauv ces qhov ceev ntawm lub tsheb tsis tas li nce 2 m/s txhua ob. Qhov ceev ntawm lub tsheb yuav nce 1 m/s ntawm thawj vib nas this, tom qab ntawd nce 3 m/s hauv vib nas this. Tab sis qhov nruab nrab, thaum txav mus rau 5 vib nas this, qhov loj ntawm qhov ceev ntawm lub tsheb yuav nce 2 m/s txhua ob.
b. Kev nrawm nrawm tam sim ntawd
Kev nrawm nrawm tam sim ntawd yog kev hloov pauv ntawm qhov ceev thaum lub sijhawm luv luv. Kev nrawm nrawm tam sim ntawd feem ntau hu ua kev nrawm nrawm. Yog li ntawd, yog tias nws hais tias yog kev nrawm nrawm, qhov txhais tau tias yog kev nrawm nrawm tam sim ntawd. Ib yam khoom raug hais tias yuav muaj kev nrawm nrawm yog tias nws qhov ceev hloov pauv. Qhov ceev kuj yog ib qho vector ntau, uas suav nrog qhov loj ntawm qhov ceev thiab kev coj ntawm qhov ceev. Yog li ntawd muaj peb qhov xwm txheej uas ib yam khoom txav mus los raug hais tias yuav nrawm nrawm. Ua ntej, ib yam khoom raug hais tias yuav muaj kev nrawm nrawm yog tias qhov loj ntawm qhov ceev lossis qhov ceev hloov pauv (qhov kev coj ntawm qhov ceev yog tas li).
Hauv thawj qhov piv txwv, lub tsheb pib nres (v = 0). Ib pliag tom qab nws qhov ceev nce mus txog 5 m/s. Qhov ceev ntawm lub tsheb nce ntxiv yog li lub tsheb thiaj li hais tias nrawm dua. Hauv qhov piv txwv thib ob, lub tsheb pib txav mus rau qhov ceev ntawm 5 m/s. Ib pliag tom qab ntawd lub tsheb nres. Qhov ceev ntawm lub tsheb txo qis vim tias lub tsheb tau hais tias muaj kev nrawm qis lossis lub tsheb tau qeeb dua. Qhov thib ob, ib yam khoom tau hais tias muaj kev nrawm yog tias qhov kev taw qhia ntawm nws qhov ceev hloov pauv (qhov loj ntawm qhov ceev lossis qhov ceev yog tas li). Qhov kev taw qhia ntawm qhov ceev = qhov kev taw qhia ntawm kev hloov chaw = qhov kev taw qhia ntawm kev txav mus los. Qhov thib peb, ib yam khoom tau hais tias muaj kev nrawm yog tias ob qho tib si qhov loj thiab qhov kev taw qhia ntawm nws qhov ceev hloov pauv.
