Tau daws cov teeb meem hauv kev txav mus los ncaj - qhov ceev tas li
1. Ib lub tsheb khiav nrog qhov ceev tas li 10 m/s. Txheeb xyuas qhov deb tom qab 10 vib nas this thiab 60 vib nas this.
tshuaj
Qhov ceev tas li 10 meters/ob txhais tau tias lub tsheb mus ncig 10 meters txhua 1 ob.
Tom qab 2 vib nas this, lub tsheb mus txog 20 meters,
Tom qab 5 vib nas this, lub tsheb mus txog 50 meters,
Tom qab 10 vib nas this, lub tsheb mus txog 100 meters ,
Tom qab 60 vib nas this, lub tsheb mus tau 600 meters.
2. Ib lub tsheb khiav raws txoj kev ncaj nraim nrog qhov ceev tas li 72 km/h. Txheeb xyuas qhov deb ntawm lub tsheb tom qab 2 feeb thiab 5 feeb.
tshuaj
72 km/teev = (72)(1000 meters) / 3600 vib nas this = 72,000 / 3600 vib nas this = 20 meters/thib ob.
Qhov ceev tas li ntawm 20 meters/ob txhais tau tias lub tsheb mus ncig 20 meters txhua 1 ob.
Tom qab 120 vib nas this los yog 2 feeb, lub tsheb mus ncig 20 meters x 120 = 2400 meters ,
Tom qab 300 vib nas this los yog 5 feeb, lub tsheb mus ncig 20 meters x 300 = 6000 meters.
3. Ib lub cev taug kev raws txoj kev ncaj nraim li 100 meters hauv 50 vib nas this. Txheeb xyuas qhov ceev ntawm lub cev.
tshuaj
100 meters / 50 vib nas this = 10 meters / 5 vib nas this = 2 meters / vib nas this.
4. Txheeb xyuas qhov ceev raws li daim duab hauv qab no….
tshuaj
Ceev = Qhov Deb / lub sijhawm dhau mus
Qhov ceev = 2 meters / 1 vib nas this = 4 meters / 2 vib nas this = 6 meters / 3 vib nas this = 8 meters / 4 vib nas this = 2 meters / vib nas this.
5. Lub tsheb A thiab B sib tsoo ntawm txoj kev sib luag. Thaum qhov deb ntawm ob lub tsheb yog 100 meters, lub tsheb A txav mus nrog qhov ceev tas li ntawm 10 m/s, lub tsheb B txav mus nrog qhov ceev tas li ntawm 40 m/s. Txheeb xyuas (a) qhov deb ntawm lub tsheb A ua ntej dhau lub tsheb B (b) lub sijhawm ua ntej lub tsheb B dhau lub tsheb A.
tshuaj
Lub Tsheb A txav mus nrog qhov ceev tas li ntawm 10 meters/ob vib nas this, txhais tau tias lub tsheb A txav mus txog 10 meters txhua 1 vib nas this. Tom qab 2 vib nas this, lub tsheb A txav mus txog 20 meters.
Lub tsheb B txav mus nrog qhov ceev tas li ntawm 40 meters/ob vib nas this, txhais tau tias lub tsheb B txav mus txog 40 meters txhua 1 vib nas this. Tom qab 2 vib nas this, lub tsheb B txav mus txog 80 meters.
20 meters + 80 meters = 100 meters.
(a) Lub tsheb A deb ua ntej dhau lub tsheb B yog 20 meters. Lub tsheb B deb ua ntej dhau lub tsheb A yog 80 meters.
(b) Lub sijhawm ntawm lub tsheb B ua ntej dhau lub tsheb A yog 2 vib nas this. Lub sijhawm ntawm lub tsheb A ua ntej dhau lub tsheb B yog 2 vib nas this
5. Yog tias lub ntsuas ceev ntawm lub tsheb qhia 108 km/h, txiav txim seb lub tsheb mus deb npaum li cas hauv ib feeb.
Tshuaj:
Lub ntsuas ceev yog ib lub cuab yeej siv los ntsuas qhov ceev. Qhov ceev ntawm lub tsheb yog 108 km/teev.
108 km/teev = (108) (1000 meters) / 3600 vib nas this = 30 meters/feeb.
1 feeb = 60 vib nas this
Qhov ceev ntawm lub tsheb 30 meters/ib pliag txhais tau tias lub tsheb txav mus txog 30 meters hauv 1 vib nas this.
Tom qab 1 vib nas this, lub tsheb txav mus deb li 1 x 30 meters = 30 meters.
Tom qab 2 vib nas this, lub tsheb txav mus deb li 2 x 30 meters = 60 meters.
Tom qab 60 vib nas this, lub tsheb txav mus deb li 60 x 30 meters = 1800 meters.
6. Tom pov pob ncaj qha rau Andrew . Tom thiab Andrew sib nrug deb li 10.08 m . Lub pob raug pov kab rov tav thiab txav mus rau 20 m/ s (tsis txhob xav txog lub ntiajteb txawj nqus). Andrew ntaus lub pob 4.00 x 10 -3 vib nas this tom qab lub pob raug pov. Yog tias tus neeg ntaus txav mus rau qhov ceev tas li ntawm 5.00 m/s, lub pob raug ntaus los ntawm tus neeg ntaus tom qab tus neeg ntaus txav mus rau...
Paub:
Qhov deb ntawm Tom thiab Andrew = 10.08 meters
Qhov ceev ntawm lub pob (v) = 20 m/s
Lub sijhawm luv (t) = 4 x 10 -3 vib nas this = 0.004 vib nas this
Qhov ceev ntawm tus neeg ntaus (v) = 5 m / s
SE pob: Lub pob raug ntaus los ntawm tus neeg ntaus tom qab lub pob txav mus deb li ...
Tshuaj:
Qhov deb ntawm pob:
s 1 = vt = (20) (0.004) = 0.08 meters
Qhov deb ntawm tus neeg ntaus:
s 2 = vt = 5 t
Qhov deb ntawm pob + qhov deb ntawm tus neeg ntaus = qhov deb ntawm Tom thiab Andrew.
0.08 + 5 t = 10.08
5 t = 10.08 – 0.08
5 t = 10
t = 10/5
t = 2 vib nas this
Qhov deb ntawm tus neeg ntaus:
s 2 = vt = 5 t = (5) (2) = 10 meters
7. Ib tug neeg yos hav zoov nrog nws lub tsheb tab tom caum ib tug mos lwj. Lub tsheb khiav ntawm 72 km/h thiab tus mos lwj khiav ntawm qhov ceev ntawm 64.8 km/h. Thaum qhov deb ntawm lub tsheb thiab tus mos lwj yog 2012 meters, tus neeg yos hav zoov tua nws rab phom tua phom. Cov mos txwv tawm ntawm rab phom ntawm 200 m/s. Txheeb xyuas lub sijhawm uas tus mos lwj raug tua.
A. 0.5 vib nas this
B. 1 s
C. 1.25 vib nas this
D. 1.5 vib nas this
Paub:
Qhov ceev ntawm lub tsheb (v b ) = 72 km / h = (72) (1000 m) / 3600 s = 20 m / s
Qhov ceev ntawm cov mos lwj (v r ) = 64.8 km / h = (64.8) (1000 m) / 3600 s = 64800 m / 3600 s = 18 m / s
Thaum lub mos txwv raug tua, qhov deb ntawm lub tsheb thiab tus mos lwj (s) = 202 meters
Qhov ceev ntawm hluav taws (v p ) = 20 m/s + 200 m/s = 220 m/s
Cov riam phom uas cov neeg yos hav zoov tuav uas nyob hauv lub tsheb uas txav mus nrog qhov ceev ntawm 20 m/s kom qhov ceev ntawm lub tsheb kuj ntxiv rau qhov ceev ntawm lub mos txwv.
Xav Tau: Txheeb xyuas lub sijhawm uas cov mos lwj raug tua
Tshuaj:
Xav txog cov tsheb thiab cov mos lwj uas txav mus los ntawm qhov ceev tas li.
Kab zauv: v = s / t los yog s = vt
v = qhov ceev, s = qhov deb, t = lub sijhawm luv
Qhov Nrug Deb = 202 + X r = 202 + v r t = 202 + 18 t
Qhov Nrug = Y p = v p t = 220 t
Qhov deb uas cov mos lwj taug kev = qhov deb uas cov mos txwv taug kev
202 + 18 t = 220 t
202 = 220 t – 18 t
202 = 202 t
t = 202/202
t = 1 vib nas this
Cov lus teb yog B.
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- Qhov nruab nrab ntawm qhov ceev thiab qhov nruab nrab ntawm qhov ceev
- Qhov ceev tas mus li
- Tsis tu ncua acceleration
- Kev txav mus los ntawm kev poob dawb
- Kev txav mus los hauv lub caij nplooj zeeg dawb
- Kev txav mus rau saum thiab nqis hauv lub caij nplooj zeeg dawb
