Piv txwv ntawm cov lus nug sib tham txog kev nce ceev
Qhov ceev yog lub tswv yim tseem ceeb hauv physics, tshwj xeeb tshaj yog hauv kinematics, ib ceg ntawm physics uas kawm txog kev txav ntawm cov khoom yam tsis xav txog qhov ua rau muaj kev txav ntawd. Lub tswv yim no tsis yog tsuas yog cuam tshuam rau hauv kev kawm xwb tab sis kuj tseem muaj nyob rau hauv kev siv txhua hnub xws li engineering, kev ua si nawv, thiab kev thauj mus los. Tsab xov xwm no yuav tham txog ntau qhov piv txwv ntawm qhov teeb meem cuam tshuam nrog qhov ceev, ua tiav nrog cov lus piav qhia ib kauj ruam zuj zus los pab nkag siab.
Lub Tswv Yim Tseem Ceeb ntawm Kev Ntxiv Ceev
Ua ntej yuav mus nug cov lus nug piv txwv, nws yuav zoo rau peb rov qab nco txog qee lub ntsiab lus yooj yim txog kev ceev thiab kev ua kom nrawm dua.
1. Qhov ceev (v) yog txhais tias yog qhov kev hloov pauv ntawm qhov chaw ib lub sijhawm.
2. Kev nrawm (a) yog ib qho ntau uas qhia txog kev hloov pauv ntawm qhov ceev hauv ib chav ntawm lub sijhawm.
Cov qauv yooj yim rau kev ua kom nrawm yog:
\[ a = \frac{\Delta v}{\Delta t} \]
Qhov twg:
- \(a \) yog qhov kev ua kom nrawm dua,
– \( \Delta v \) yog qhov kev hloov pauv ntawm qhov ceev,
- \( \Delta t \) yog lub sijhawm luv.
Piv txwv lus nug 1
Lo lus nug:
Thaum xub thawj, lub tsheb khiav ceev li ntawm 10 m/s. Tom qab 5 vib nas this, lub tsheb yuav khiav ceev li ntawm 20 m/s. Lub tsheb khiav ceev nruab nrab li cas?
Kev Sib Tham:
Nws paub tias:
– Qhov ceev pib (\( v_0 \)) = 10 m/s,
– Qhov ceev kawg (\( v_f \)) = 20 m/s,
- Lub Sijhawm (\( \Delta t \)) = 5 vib nas this.
Peb siv tau cov qauv acceleration:
\[ a = \frac{v_f – v_0}{\Delta t} \]
Hloov cov nqi uas paub lawm:
\[ ib = \frac{20 – 10}{5} \]
\[ ib = \frac{ 10 }{ 5 } \]
\[ a = 2 \, \text{m/s}^2 \]
Yog li, qhov nruab nrab ntawm kev nrawm ntawm lub tsheb yog 2 m / s².
Piv txwv lus nug 2
Lo lus nug:
Ib lub tsheb ciav hlau pib ntawm qhov chaw so thiab mus txog qhov ceev ntawm 30 m/s hauv 10 vib nas this. Xam nws qhov nruab nrab ntawm qhov kev nrawm thiab qhov deb uas tau mus thaum lub sijhawm ntawd.
Kev Sib Tham:
Kev nrawm:
Nws paub tias:
- Qhov ceev pib (\( v_0 \)) = 0 m/s (vim nws pib los ntawm lub xeev ruaj khov),
– Qhov ceev kawg (\( v_f \)) = 30 m/s,
- Lub Sijhawm (\( \Delta t \)) = 10 vib nas this.
Siv cov qauv acceleration:
\[ a = \frac{v_f – v_0}{\Delta t} = \frac{30 – 0}{10} = 3 \, \text{m/s}^2 \]
Qhov deb uas tau mus:
Yuav xam qhov deb (\( s \)) tau mus ncig, peb siv tau ib qho ntawm cov qauv kinematic:
\[ s = v_0 t + \frac{1}{2} ntawm ^2 \]
Hloov cov nqi uas paub lawm:
\[ s = 0 \cdot 10 + \frac{1}{2} \cdot 3 \cdot (10)^2 \]
\[ s = \frac{1}{2} \cdot 3 \cdot 100 \]
\[ s = 150 \, \text{m} \]
Yog li, qhov deb uas lub tsheb ciav hlau taug kev yog 150 meters.
Piv txwv lus nug 3
Lo lus nug:
Ib lub maus taus sawv ntawm ib qho chaw thiab pib txav mus los nrog qhov nrawm tas li ntawm 4 m/s². Tom qab txav mus los rau 8 vib nas this, qhov ceev kawg thiab qhov deb uas lub maus taus taug kev yog dab tsi?
Kev Sib Tham:
Qhov ceev kawg:
Nws paub tias:
- Qhov ceev pib (\( v_0 \)) = 0 m/s (vim nws pib los ntawm lub xeev ruaj khov),
– Kev nrawm (\( a \)) = 4 m/s²,
- Lub sijhawm (\( t \)) = 8 vib nas this.
Siv cov qauv ceev:
\[ v_f = v_0 + at \]
Hloov cov nqi uas paub lawm:
\[ v_f = 0 + 4 \cdot 8 \]
\[ v_f = 32 \, \text{m/s} \]
Qhov deb uas tau mus:
Siv cov qauv ntsuas qhov deb:
\[ s = v_0 t + \frac{1}{2} ntawm ^2 \]
Hloov cov nqi uas paub lawm:
\[ s = 0 \cdot 8 + \frac{1}{2} \cdot 4 \cdot (8)^2 \]
\[ s = \frac{1}{2} \cdot 4 \cdot 64 \]
\[ s = 128 \, \text{m} \]
Yog li, tom qab txav mus rau 8 vib nas this, qhov ceev kawg ntawm lub maus taus yog 32 m / s thiab qhov deb uas nws tau mus yog 128 meters.
Piv txwv lus nug 4
Lo lus nug:
Ib lub pob raug pov ntsug rau saum ntuj nrog qhov ceev pib ntawm 20 m/s. Tom qab mus txog qhov siab tshaj plaws, lub pob poob rov qab rau hauv av nrog qhov nrawm vim lub ntiajteb txawj nqus \( g = 9.8 \, \text{m/s}^2 \). Nws siv sijhawm ntev npaum li cas rau lub pob kom mus txog hauv av dua?
Kev Sib Tham:
Lub sijhawm uas siv los nce thiab nqis yog tib yam. Yog li peb tsuas yog yuav tsum xam lub sijhawm uas siv los nce, tom qab ntawd muab nws faib rau 2 kom tau tag nrho lub sijhawm.
Nws paub tias:
– Qhov ceev pib (\( v_0 \)) = 20 m/s,
- Qhov ceev ntawm qhov chaw siab tshaj plaws (\( v_f \)) = 0 m / s (vim tias nws nres ib pliag),
- Kev nrawm vim lub ntiajteb txawj nqus (g) = 9.8 m/s².
Siv cov qauv ceev:
\[ v_f = v_0 + (-g) t \]
Hloov cov nqi uas paub lawm:
\[ 0 = 20 – 9.8 t \]
\[ 9.8 t = 20 \]
\[ t = \frac{20}{9.8} \]
\[ t \approx 2.04 \, \text{s} \]
Nov yog lub sijhawm rau lub pob mus txog nws qhov chaw siab tshaj plaws. Yog li, tag nrho lub sijhawm rau kev nce thiab nqis yog:
\[ 2 \cdot 2.04 \kwv yees li 4.08 \, \text{s} \]
Yog li, tag nrho lub sijhawm uas nws siv rau lub pob kom mus txog hauv av dua yog li 4.08 vib nas this.
Xaus
Hauv txhua qhov teeb meem uas tau tham saum toj no, kauj ruam tseem ceeb yog nkag siab txog cov ntsiab lus tseem ceeb ntawm qhov ceev thiab kev nrawm thiab lawv siv li cas hauv cov qauv tshwj xeeb. Txawm hais tias cov teeb meem sib txawv, txoj hauv kev ua raws li cov ntsiab cai tseem ceeb ntawm physics. Vam tias los ntawm kev xyaum cov teeb meem no, cov tub ntxhais kawm yuav nkag siab tob dua txog qhov ceev thiab kev nrawm cuam tshuam li cas hauv kev txav ntawm cov khoom.
Tau kawg, nyob rau hauv kev siv txhua hnub, kev nkag siab txog lub tswv yim no tuaj yeem pab tau zoo heev, tsis yog tsuas yog hauv kev kawm xwb tab sis kuj nyob rau hauv ntau yam kev tshaj lij xws li engineering, kev thauj mus los, thiab lwm yam. Nco ntsoov nco ntsoov nkag siab txog qhov teeb meem ua ntej, ua ntej sim daws nws, yog li cov txheej txheem ntawm kev nkag siab thiab daws qhov teeb meem yuav yooj yim dua thiab ua haujlwm tau zoo dua.
