Kev txav mus los ncaj qha - teeb meem thiab kev daws teeb meem

Kev txav mus los ncaj qha - teeb meem thiab kev daws teeb meem

1. Daim duab qhia txog qhov ceev (v) piv rau lub sijhawm (t) uas qhia hauv daim duab hauv qab no. Qhov qeeb qeeb raws li daim duab qhia yog dab tsi.

tshuaj

AB = kev txav mus los ntawm kev nrawm tas li , BC = kev txav mus los ntawm kev nrawm tas li , CD = kev txav mus los ntawm kev qeeb tas li.

2. Daim duab qhia txog kev txav mus los uas qhia nyob rau hauv daim duab hauv qab no. Qhov deb uas ib yam khoom taug kev los ntawm 0 vib nas this - 8 vib nas this yog dab tsi.

tshuaj

Cheeb Tsam 1 = daim duab peb ceg cheeb tsam = ½ (4-0)(12-0) = ½ (4)(12) = (2)(12) = 24

Cheeb Tsam 2 = Lub duab plaub fab = (8-4)(12-0) = (4)(12) = 48

Qhov deb tau mus ncig hauv 8 vib nas this = 24 meters + 48 meters = 72 meters.

3. Daim duab qhia txog qhov ceev (v) piv rau lub sijhawm (t) rau kev txav mus los ncaj qha raws li qhia hauv daim duab hauv qab no. Qhov deb uas tau mus ncig hauv 12 vib nas this yog dab tsi.

tshuaj

Cheeb Tsam 1 = cheeb tsam ntawm daim duab peb sab = ½ (2-0)(4-0) = ½ (2)(4) = 4

Cheeb Tsam 2 = cheeb tsam ntawm lub duab plaub fab = (6-2)(4-0) = (4)(4) = 16

Cheeb Tsam 3 = cheeb tsam ntawm daim duab peb sab = ½ (8-6)(4-0) = ½ (2)(4) = 4

Cheeb Tsam 4 = cheeb tsam ntawm daim duab peb sab = ½ (10-8)(4-0) = ½ (2)(4) = 4

Cheeb Tsam 5 = cheeb tsam ntawm lub xwmfab = (12-10)(4-0) = (2)(4) = 8

Qhov deb uas taug kev hauv 12 vib nas this = 4 + 16 + 4 + 4 + 8 = 36 meters

4. Ib yam khoom khiav nrawm li 36 km/teev li 5 vib nas this, ces khiav nrawm li 1 m/s ^li 10 vib nas this thiab ces qeeb qeeb li 2 m/s ^kom txog thaum nws so. Daim duab (vt) qhia txog kev khiav ntawm yam khoom.

Paub:

Kev txav mus los 1 = qhov ceev tas li

Qhov ceev tas mus li (v) = 36 km/h = 36 (1000 m) / 3600 s = 36,000 m / 3600 s = 10 m/s

Lub sijhawm luv (t) = 5 vib nas this

Kev txav mus los 2 = kev nrawm tas mus li

Qhov ceev pib (v _o ) = qhov ceev thaum txav mus los 1 = 10 m/s

Kev nrawm (a) = 1 m/s ²

Lub sijhawm luv (t) = 10 vib nas this

Kev txav mus los 3 = kev qeeb qeeb tas li

Kev qeeb qeeb (a) = -2 m/s ²

Qhov ceev kawg (v _t ) = 0 m/s

Xav tau: daim duab qhia txog kev mus ncig ntawm yam khoom

Tshuaj:

Qhov ceev kawg ntawm kev txav mus los 2:

vt ₌ v0 ₊ at

v _t = 10 + (1)(10) = 10 + 10 = 20 m/s

Qhov ceev kawg ntawm kev txav mus los 2 (v _t ) = qhov ceev pib ntawm kev txav mus los 3 (v _o ) = 20 m/s

Lub sijhawm sib nrug ntawm kev txav mus los 3:

vt ₌ v0 ₊ at

0 = 20 + (-2)(t)

0 = 20 – 2t

20 = 2t

t = 20/2

t = 10 vib nas this

Kev Tawm Tsam 1: Khoom mus ncig ntawm qhov ceev tas li 10 m/s hauv 5 vib nas this

Kev Tawm Tsam 2: Khoom tau nrawm dua hauv 10 vib nas this kom txog thaum nws qhov ceev = 20 m/s.

Kev Tawm Tsam 3: Khoom qeeb qeeb hauv 10 vib nas this kom txog thaum so.

Daim duab B qhia txog kev mus ncig ntawm yam khoom.

5. Lub tsheb khiav ceev li ntawm 5 m/s tas li hauv 10 vib nas this, ces nws khiav nrawm li ntawm 1 m/s ² hauv 5 vib nas this. Ces nws qeeb qeeb mus txog thaum lub tsheb nres tom qab nws khiav tau 137.5 meters. Daim duab (vt) qhia txog kev mus ncig ntawm yam khoom.

Paub:

Kev txav mus los 1 = kev txav mus los ntawm qhov ceev tas li

Qhov ceev tas mus li (v) = 5 m/s

Lub sijhawm luv (t) = 10 vib nas this

Kev txav mus los 2 = kev txav mus los ntawm kev nrawm tas li

Qhov ceev pib (v _o ) = qhov ceev thaum txav mus los 1 = 5 m/s

Kev nrawm (a) = 1 m/s ²

Lub sijhawm luv (t) = 5 vib nas this

Qhov ceev kawg (v _t ) = 0 m/s

Tag nrho qhov deb (s) = 137.5 m/s

Xav tau: Daim duab qhia txog kev mus ncig ntawm lub tsheb

Tshuaj:

Qhov nrug rau kev txav mus los 1:

s = vt = (5)(10) = 50 meters

Qhov nrug rau kev txav mus los 2:

s = v _o t + ½ ntawm ² = (5)(5) + ½ (1)(5) ² = 25 + ½ (25) = 25 + 12.5 = 37.5 meters

Qhov nrug rau kev txav mus los 3:

137.5 – (50 + 37.5) = 137.5 – 87.5 = 50 meters

Qhov ceev kawg ntawm kev txav mus los 2:

Qhov ceev kawg ntawm kev txav mus los 2 xam los ntawm kev siv cov ntaub ntawv ntawm kev txav mus los 2:

vt ₌ v0 ₊ at

v _t = 5 + (1)(5) = 5 + 5 = 10 m/s

Qhov ceev kawg rau kev txav mus los 2 (v _t ) = qhov ceev pib rau kev txav mus los 3 (v _o ) = 10 m/s

Lub sijhawm luv rau kev txav mus los 3:

Lub sijhawm luv tau suav tom qab nrhiav pom qhov qeeb. Qhov qeeb (a) thiab lub sijhawm luv (t) suav siv cov ntaub ntawv ntawm kev txav mus los 3.

Kev qeeb ntawm cov khoom thaum txav mus los 3:

v _t ² = v _o ² + 2 ad

0 ² = 10 ² + 2 a (50)

0 = 100 + 100 a

100 = -100 ib

ib = – 100 / 100

ib = – 1 m/s ²

Lub sijhawm sib nrug ntawm kev txav mus los 3:

vt ₌ v0 ₊ at

0 = 10 + (-1) t

0 = 10 – t

t = 10 vib nas this

Kev Tawm Tsam 1: Khoom mus ncig ntawm qhov ceev tas li 5 m/s hauv 10 vib nas this.

Kev Tawm Tsam 2: Khoom mus ncig li 5 vib nas this kom txog thaum nws qhov ceev = 10 m/s.

Kev Tawm Tsam 3: Khoom qeeb qeeb li 10 vib nas this kom txog thaum so.

6. Ib lub tsheb hnyav 800-kg mus raws ib txoj kab ncaj nrog qhov ceev pib ntawm 36 km/teev. Tom qab mus txog 150 meters, qhov ceev ntawm lub tsheb = 72 km/teev. Txheeb xyuas lub sijhawm sib nrug.

Paub:

vo = 36 km/teev = 36,000 meters / 3600 vib nas this = 10 m/ _s

v _t = 72 km/teev = 72,000 meters / 3600 vib nas this = 20 m/s

d = 150 meters

Xav tau: lub sijhawm sib nrug (t)

Tshuaj:

Peb qhov kev sib npaug ntawm kev txav mus los ntawm kev nrawm tas mus li:

vt ₌ v0 ₊ at

d = v _ot + ½ ntawm ²

v _t ² = v _o ² + 2 ad

Kev nrawm:

v _t ² = v _o ² + 2 ad

20 ² = 10 ² + 2 a (150)

400 = 100 + 300 a

400 – 100 = 300 ib

300 = 300 ib

ib = 300 / 300

a = 1 m/s ²

Lub Sijhawm Sib Nrug:

vt ₌ v0 ₊ at

20 = 10 + (1) t

20 – 10 = t

t = 10 vib nas this

7. Ib lub tsheb khiav ceev tas li ntawm 20 m/s. Lub tsheb nres hauv 5 vib nas this tom qab qeeb qeeb. Lub tsheb mus deb npaum li cas.

Paub:

Qhov ceev pib ( _v₂o ) = 20 m/s

Qhov ceev kawg (v _t ) = 0 m/s

Lub sijhawm luv (t) = 5 vib nas this

Xav tau: qhov deb (d)

Tshuaj:

kev qeeb qeeb:

vt ₌ v0 ₊ at

0 = 20 + 5

-20 = 5a

ib = -20/5

a = -4 m/s ²

Kev ncua deb ntawm lub tsheb mus:

d = vot ₊ 1/2 ntawm ²

d = (20)(5) + 1/2 (-4)(5) ² = (20)(5) + (-2)(25)

d = 100 – 50

d = 50 meters

8. Qhov nrug thiab lub sijhawm ntawm ib yam khoom txav tau qhia nyob rau hauv lub rooj hauv qab no.

Txheeb xyuas hom kev txav uas cov khoom 1 thiab 2 tau ntsib…

tshuaj

Khoom 1:

v = s / t

v = qhov ceev , s = qhov deb , t = lub sijhawm luv

v = 60/15 = 4 cm/s

v = 80/20 = 4 cm/s

v = 100/25 = 4 cm/s

Qhov ceev tas li = kev txav mus los ncaj nraim.

Khoom 2:

v = s / t

v = qhov ceev, s = qhov deb , t = lub sijhawm luv

v = 4/2 = 2 cm/s

v = 9/3 = 3 cm/s

v = 25/5 = 5 cm/s

Qhov ceev nce ntxiv = kev txav mus los tsis sib xws, nrawm dua.

1. Lus Nug: Dab tsi ua rau kev txav mus los ncaj qha txawv ntawm lwm hom kev txav mus los? teb: Kev txav mus los ncaj qha txhais tau tias yog kev txav mus los ntawm ib yam khoom mus rau ib txoj kev ncaj nraim. Tsis zoo li kev txav mus los tig lossis kev co, tsis muaj kev hloov pauv ntawm kev txav mus los ntawm ib yam khoom mus rau lwm yam hauv kev txav mus los ncaj qha.
2. Lus Nug: Qhov deb txawv li cas ntawm kev hloov chaw hauv kev txav mus los linear? teb: Qhov deb yog qhov ntev tag nrho ntawm txoj kev uas ib yam khoom taug kev, thaum qhov kev hloov chaw yog qhov kev ncua deb ntawm txoj haujlwm pib thiab qhov kawg, nrog rau kev taw qhia. Qhov kev hloov chaw yog ib qho vector, thaum qhov deb yog scalar.
3. Lus Nug: Vim li cas qhov ceev thiab qhov nrawm thiaj li muaj cov nqi sib txawv rau tib qho kev txav mus los? teb: Qhov ceev yog qhov ntsuas scalar ntawm qhov ceev npaum li cas ib yam dab tsi txav mus yam tsis xav txog nws qhov kev taw qhia, thaum qhov ceev yog qhov ntau vector uas suav nrog ob qho tib si qhov loj thiab kev taw qhia. Rau kev txav mus los linear, yog tias muaj kev hloov pauv hauv kev taw qhia, qhov nruab nrab qhov ceev yuav txawv ntawm qhov loj ntawm qhov nruab nrab qhov ceev.
4. Lus Nug: Txhais li cas thaum peb hais tias ib yam khoom muaj kev txav mus los ncaj nraim? teb: Ib yam khoom uas txav mus los ncaj nraim thiab nrawm tas li, txav mus rau hauv ib txoj kab ncaj nraim nrog qhov ceev tas li. Qhov no txhais tau tias nws qhov ceev thiab kev coj tseem tsis hloov pauv raws sijhawm.
5. Lus Nug: Ib yam khoom yuav muaj qhov ceev tas li tab sis qhov ceev hloov pauv li cas hauv kev txav mus los ncaj? teb: Rau ib yam khoom uas txav mus los ua kab ncaj, tib txoj kev uas qhov no yuav tshwm sim tau yog tias qhov kev taw qhia ntawm kev txav mus los hloov pauv. Txawm li cas los xij, hauv kev txav mus los ua kab ncaj tiag tiag, qhov kev taw qhia tseem zoo ib yam. Yog tias qhov kev taw qhia hloov pauv, nws tsis yog kev txav mus los ua kab ncaj xwb.
6. Lus Nug: Kev ua kom nrawm ua lub luag haujlwm dab tsi hauv kev txav mus los ncaj? teb: Kev nrawm qhia txog kev hloov pauv ntawm qhov ceev raws sijhawm. Hauv kev txav mus los ncaj, qhov no txhais tau tias kev nce lossis txo qhov ceev lossis kev hloov pauv ntawm kev taw qhia (yog tias kev txav mus los tsis yog ncaj xwb). Kev nrawm tsis yog xoom qhia tias qhov ceev ntawm yam khoom hloov pauv.
7. Lus Nug: Kev nrawm tsis zoo, lossis kev qeeb qeeb, tshwm sim li cas hauv kev txav mus los ncaj? teb: Hauv cov ntsiab lus ntawm kev txav mus los ncaj, kev nrawm tsis zoo (feem ntau hu ua kev qeeb) txhais tau tias kev txo qis ntawm qhov ceev raws tib txoj kev ncaj. Nws yog kev nrawm hauv qhov kev taw qhia tawm tsam kev txav mus los.
8. Lus Nug: Raws li Newton txoj cai thib ob, kev sib raug zoo ntawm lub zog net thiab kev ua kom nrawm dua hauv kev txav mus los linear yog dab tsi? teb: Raws li Newton txoj cai thib ob, lub zog ua haujlwm rau ib yam khoom yog proportional rau qhov kev nrawm uas nws dhau los thiab ua haujlwm rau tib qho kev coj. tshwj xeeb, $F=ma$, qhov twg $F$ yog lub zog tiag tiag, $m$ yog qhov hnyav ntawm yam khoom, thiab $a$ yog nws qhov kev nrawm.
9. Lus Nug: Yog tias lub tsheb txav mus rau hauv ib txoj kab ncaj thiab nres, peb puas hais tau tias nws qhov kev hloov pauv zaum kawg yog xoom? teb: Tsis yog. Kev hloov chaw yog hais txog qhov deb ntawm txoj kab ncaj nraim ntawm qhov chaw pib thiab qhov chaw kawg nrog kev taw qhia. Yog tias lub tsheb tau txav mus los ntawm nws qhov chaw pib ua ntej nres, qhov kev hloov chaw tsis yog xoom; tsuas yog nws qhov ceev kawg xwb.

10. Lo lus nug: Lub tswv yim ntawm inertia muaj feem cuam tshuam li cas rau kev txav mus los ncaj nraim? Lus teb: Inertia yog qhov kev tiv thaiv ntawm ib yam khoom rau kev hloov pauv hauv nws lub xeev ntawm kev txav mus los. Rau ib yam khoom hauv kev txav mus los ncaj nraim, inertia txhais tau hais tias yam khoom yuav txuas ntxiv mus rau hauv ib txoj kab ncaj nraim ntawm qhov ceev tas li tshwj tsis yog tias muaj lub zog sab nraud ua rau.