12 Piv Txwv ntawm Cov Lus Nug Txog Kev Sib Tsoo Lub Zog
1. QhaIb lub mos txwv roj hmab uas zoo li lub pob uas muaj qhov hnyav ntawm 40 grams raug tua kab rov tav mus rau ntawm phab ntsa raws li pom hauv daim duab. Yog tias lub pob dhia ntawm tib qhov ceev, ces qhov kev hloov pauv ntawm lub zog ntawm lub pob yog a
dalah…
A. 2 Ns
B. 3 Ns
C. 4 Ns
D. 5 Ns
E. 6 Ns
Kev Sib Tham
Nws yog paub tias :
Qhov hnyav (m) = 40 grams = 0,04 kg
Qhov ceev pib ( v₂o ) = – 50 m/s
Qhov ceev kawg (v t ) = 50 m/s
Qhov kev taw qhia ntawm lub pob txav mus los (qhov kev taw qhia ntawm qhov ceev) yog qhov sib txawv, yog li ntawd qhov ceev pib thiab qhov ceev kawg muaj cov cim sib txawv.
Nug : pes tsawg qhov kev hloov pauv ntawm lub zog ntawm lub pob
Lus teb :
Cov qauv hloov pauv momentum:
Δp = m (vt – vo o ) = (0,04)(50 – (-50)) = (0,04)(50 + 50)
Δp = (0,04)(100) = 4 Ns
Cov lus teb yog C.
2. Muab ib lub pob roj hmab hnyav 75-gram pov rau kab rov tav kom txog thaum nws ntaus phab ntsa raws li pom hauv daim duab. Yog tias lub pob roj hmab dhia rov qab nrog tib qhov ceev, ces qhov loj ntawm lub zog uas tshwm sim yog...
A. 0
B. 1,5 Ns
C. 3,0 Ns
D. 3,7 Ns
E. 5,5 Ns
Kev Sib Tham
Nws yog paub tias :
Qhov hnyav ntawm lub pob (m) = 75 grams = 0,075 kg
Qhov ceev pib ( v₂o ) = -20 m/s
Qhov ceev kawg (v t ) = 20 m/s
Qhov kev taw qhia ntawm lub pob txav mus los (qhov kev taw qhia ntawm qhov ceev) yog qhov sib txawv, yog li ntawd qhov ceev pib thiab qhov ceev kawg muaj cov cim sib txawv.
Nug : kev xav
Lus teb :
Impulse = kev hloov pauv ntawm momentum
Kuv = Δp
Kuv = m (vt – vo o ) = 0,075 (20 – (-20)) = 0,075 (20 + 20) = 0,075 (40)
Kuv = 3 Ns
Ns sawv cev rau Newton thib ob.
Cov lus teb yog C.
3. Ob yam khoom uas muaj tib lub cev hnyav txav mus rau ib txoj kab ncaj nraim raws li pom hauv daim duab!
Yog tias v 2 ' yog qhov ceev ntawm yam khoom (2) tom qab kev sib tsoo mus rau sab xis nrog qhov ceev ntawm 5 ms -1 , ces qhov loj ntawm qhov ceev v 1 ' (1) tom qab kev sib tsoo yog…..
A. 7 ms-1
B. 9 ms −1
C. 13 ms −1
D. 15 ms −1
E. 17 ms −1
Kev Sib Tham
Nws paub tias:
Qhov hnyav ntawm ob yam khoom yog tib yam = m
Qhov ceev ntawm yam khoom 1 ua ntej kev sib tsoo (v 1 ) = 8 m/s
Qhov ceev ntawm yam khoom 2 ua ntej kev sib tsoo (v 2 ) = 10 m/s
Qhov ceev ntawm yam khoom 2 tom qab kev sib tsoo (v 2 ') = 5 m/s
Lo lus nug: Qhov ceev ntawm yam khoom 1 tom qab sib tsoo (v 1 ')
Lus teb:
Qhov no yog kev sib tsoo tsis zoo tag nrho. v 1 ' yog xam siv txoj cai ntawm kev txuag lub zog:
m 1 v 1 + m 2 v 2 = m 1 v 1 ' + m 2 v 2 '
m (v 1 + v 2 ) = m (v 1 ' + v 2 ' )
v 1 + v 2 = v 1 ' + v 2 '
8 + 10 = v1 ' + 5
18 = v1 ' + 5
v 1 ' = 18-5
v 1 ' = 13 m/s
Cov lus teb yog C.
4. Ob lub pob, txhua lub muaj qhov hnyav m 1 = 2 kg thiab m 2 = 1 kg, dov mus rau hauv qhov sib txawv nrog qhov ceev v 1 = 2 m s -1 thiab v 2 = 4 m s -1 raws li pom hauv daim duab hauv qab no. Ob lub pob ces sib tsoo thiab tom qab sib tsoo lawv lo ua ke. Qhov ceev ntawm ob lub pob tom qab sib tsoo yog…
A. 2 ms-1
B. 1,2 ms -1
C. 1 ms -1
D. 0,5 ms -1
E. xoom
Kev Sib Tham
Nws yog paub tias :
Qhov hnyav ntawm lub pob 1 (m 1 ) = 2 kg
Qhov hnyav ntawm lub pob 2 (m 2 ) = 1 kg
Qhov ceev ntawm lub pob 1 ua ntej sib tsoo (v 1 ) = 2 m/s
Qhov ceev ntawm lub pob 2 ua ntej sib tsoo (v 2 ) = -4 m/s
Qhov ceev yog qhov zoo thiab qhov tsis zoo vim tias qhov kev taw qhia ntawm lub pob txav mus rau sab nraud. Cov cim zoo thiab qhov tsis zoo qhia txog qhov kev taw qhia ntawm lub pob txav mus.
Lo lus nug : Qhov ceev ntawm lub pob tom qab kev sib tsoo (v')
Lus teb :
Lo lus nug no hais txog kev sib tsoo tsis sib luag. Hauv kev sib tsoo tsis sib luag, txoj cai ntawm kev txuag lub zog kinetic tsis siv tau, thiab tsuas yog txoj cai ntawm kev txuag lub zog momentum siv tau. Qhov ceev ntawm lub pob tom qab kev sib tsoo yog xam los ntawm kev siv cov mis rau txoj cai ntawm kev txuag lub zog momentum.
m 1 v 1 + m 2 v 2 = (m 1 + m 2 ) v'
(2)(2) + (1)(-4) = (2 + 1) v'
4 – 4 = (3) v'
0 = (3) v'
v' = 0
Cov lus teb yog yog E.
5. Ob lub pob A thiab B muaj tib lub cev sib npaug zos txav mus rau ib leeg nrog qhov ceev ntawm 4 ms -1 thiab 6 ms -1 raws li pom hauv daim duab! Ob leeg ces sib tsoo elastically, thiab qhov ceev ntawm yam khoom B tom qab sib tsoo yog 4 ms -1 nyob rau hauv qhov kev taw qhia rov qab ntawm nws thawj qhov kev txav mus los. Qhov ceev ntawm lub pob A tam sim ntawd tom qab sib tsoo yog...
A. 2 ms-1
B. 2,5 ms -1
C. 4 ms -1
D. 5 ms -1
E. 6 ms -1
Kev Sib Tham
Nws yog paub tias :
Qhov hnyav ntawm lub pob A (m A ) = m
Qhov hnyav ntawm lub pob B (mB ) = m
Qhov ceev ntawm lub pob A ua ntej kev sib tsoo (v A ) = 4 m/s
Qhov ceev ntawm lub pob B ua ntej kev sib tsoo (v B ) = 6 m/s
Qhov ceev ntawm lub pob B tom qab kev sib tsoo (v B ') = 4 m/s
Lo lus nug : Qhov ceev ntawm lub pob A tom qab kev sib tsoo (v A ')
Lus teb :
Yog tias ob yam khoom uas sib tsoo elastically muaj tib lub qhov hnyav, ces tom qab kev sib tsoo ob yam khoom pauv qhov ceev.
Qhov ceev ntawm lub pob A ua ntej kev sib tsoo (v A ) = qhov ceev ntawm lub pob B tom qab kev sib tsoo (v B ') = 4 m/s
Qhov ceev ntawm lub pob B ua ntej kev sib tsoo (v B ) = qhov ceev ntawm lub pob A tom qab kev sib tsoo (v A ') = 6 m/s
Yog tias lub pob A txav mus rau sab laug ua ntej kev sib tsoo, tom qab ntawd tom qab kev sib tsoo, lub pob A txav mus rau sab xis. Ib yam li ntawd, yog tias lub pob B txav mus rau sab xis ua ntej kev sib tsoo, tom qab ntawd tom qab kev sib tsoo, lub pob B txav mus rau sab laug. Yog li, hauv kev sib tsoo zoo meej, qhov kev taw qhia ntawm kev txav mus los ntawm cov khoom ua ntej thiab tom qab kev sib tsoo yog qhov sib txawv.
Cov lus teb yog yog E.
6. Cov khoom A thiab B, txhua yam muaj qhov hnyav 4 kg thiab 5 kg, txav mus rau hauv cov kev taw qhia sib txawv raws li pom hauv daim duab. Tom qab ntawd lawv sib tsoo thiab tom qab kev sib tsoo, ob yam khoom tig rov qab nrog qhov ceev ntawm A = 4 ms -1 thiab qhov ceev ntawm B = 2 ms -1 . Yog li ntawd, qhov ceev ntawm cov khoom B ua ntej kev sib tsoo yog...
A. 6,0 ms-1
B. 3,0 ms -1
C. 1,6 ms -1
D. 1,2 ms -1
E. 0,4 ms -1
Kev Sib Tham
Nws yog paub tias :
Qhov hnyav ntawm yam khoom A (m A ) = 4 kg
Qhov hnyav ntawm yam khoom B (mB ) = 5 kg
Qhov ceev ntawm yam khoom A ua ntej kev sib tsoo (v A ) = 6 m/s
Qhov ceev ntawm yam khoom A tom qab kev sib tsoo (v A ') = 4 m/s
Qhov ceev ntawm yam khoom B tom qab kev sib tsoo (v B ') = -2 m/s
Cov cim zoo thiab tsis zoo piav qhia txog qhov kev taw qhia ntawm lub pob.
Lo lus nug : Qhov ceev ntawm yam khoom B ua ntej kev sib tsoo (v B )
Lus teb :
Qhov teeb meem no tsis piav qhia txog hom kev sib tsoo. Txawm li cas los xij, raws li qhov ntau thiab tsawg paub, nws xaus lus tias qhov teeb meem no cuam tshuam nrog kev sib tsoo ib nrab elastic lossis kev sib tsoo tsis zoo tag nrho elastic. Hauv kev sib tsoo ib nrab elastic, txoj cai ntawm kev txuag lub zog kinetic tsis siv; tsuas yog txoj cai ntawm kev txuag lub zog momentum siv tau. Lub zog ntawm khoom B ua ntej kev sib tsoo yog suav los ntawm kev siv txoj cai ntawm kev txuag lub zog momentum.
m A v A + m B v B = m A v A ' + m B v B '
(4)(6) + (5)(-2) = (4)(4) + (5)(vB ' )
24 – 10 = 16 + 5(vB ' )
14 – 16 = 5 (vB ' )
-2 = 5 (vB ' )
vB ' = -2/5
vB ' = -0,4
Lub cim tsis zoo txhais tau hais tias qhov kev taw qhia ntawm kev txav mus los ntawm yam khoom B tom qab kev sib tsoo yog qhov sib txawv rau qhov kev taw qhia ntawm yam khoom ua ntej kev sib tsoo.
Cov lus teb yog yog E.
7. Ib lub pob 200-gram raug poob ntawm qhov siab 80 cm tsis muaj qhov pib ceev. Tom qab ntaus hauv pem teb, lub pob rov qab nrog qhov ceev ntawm 1 ms -1 (g = 10 ms -2 ). Qhov loj ntawm lub zog ntawm lub pob yog...
A. 1,6 Ns
B. 1,5 Ns
C. 1,0 Ns
D. 0,8 Ns
E. 0,6 Ns
Kev Sib Tham
Nws paub tias:
Qhov hnyav ntawm lub pob = 200 grams = 0,2 kg
Qhov siab = 80 cm = 0,80 m
Qhov ceev ntawm lub pob ua ntej ntaus hauv pem teb = ....
Qhov ceev ntawm lub pob tom qab ntaus hauv pem teb / lub pob dhia = 1 m/s
Kev nrawm vim lub ntiajteb txawj nqus (g) = 10 m/s 2
Lo lus nug: Qhov loj ntawm lub zog (I)
Lus teb:
Qhov ceev ntawm lub pob ua ntej ntaus hauv pem teb
Ua ntej, xam qhov ceev ntawm lub pob ua ntej nws ntaus hauv pem teb, siv cov mis ntawm kev poob dawb.
Nws paub tias:
Qhov siab (h) = 80 cm = 0,8 m
Kev nrawm vim lub ntiajteb txawj nqus (g) = 10 m/s 2
Lo lus nug: Qhov ceev kawg (v t )
Lus teb:
v t 2 = 2 gh = 2(10)(0,8) = 2(8) = 16
v t = √ 16 = 4 m/s
Qhov loj ntawm lub zog impulse (I)
Nws paub tias:
Qhov hnyav ntawm lub pob (m) = 200 grams = 0,2 kg
Qhov ceev ntawm lub pob ua ntej ntaus hauv pem teb (v o ) = -4 m/s
Qhov ceev ntawm lub pob tom qab ntaus hauv pem teb / lub pob dhia (v t ) = 1 m/s
Qhov kev taw qhia ntawm lub pob txav mus los yog qhov kev taw qhia ntawm qhov ceev ntawm lub pob sib txawv yog li ib qho ceev yog qhov zoo, qhov tod tes ceev yog qhov tsis zoo.
Nug: Impulse (Kuv)
Lus teb:
Cov lus qhia txog kev txav mus los ntawm lub zog (impulse-momentum theorem) hais tias kev txav mus los = kev hloov pauv ntawm lub zog (momentum). Hauv lej:
Kuv = Δp
Kuv = m ( vt – vo )
Kuv = (0,2)(1– (-4))
Kuv = (0,2)(1 + 4)
Kuv = (0,2)(5)
Kuv = 1 Ns
Cov lus teb yog C.
8. Saib daim duab hauv qab no!
Ob yam khoom uas muaj tib qhov hnyav m 1 = m 2 = 0,5 kg raug tso tawm tib lub sijhawm los ntawm tib qhov siab raws txoj kev du thiab concave nrog lub vojvoog ntawm 1/5 'meter'. Yog tias ob yam khoom sib tsoo zoo kawg nkaus elastically, ces qhov ceev ntawm txhua yam khoom tom qab kev sib tsoo yog ... (g = 10 m s -1 )
A. v'1 = -1 ms-1 ; v'2 = 2 ms-1
B. v' 1 = +1 ms -1 ; v' 2 = -2 ms -1
C. v' 1 = -2 ms -1 ; v' 2 = +2 ms -1
D. v' 1 = -2 ms -1 ; v' 2 = +3 ms -1
E. v' 1 = +3 ms -1 ; v' 2 = -2 ms -1
Kev Sib Tham
Nws paub tias:
Qhov hnyav ntawm yam khoom (m) = m 1 = m 2 = 0,5 kg
Qhov siab pib (h 1 ) = 1/5 'meter'
Qhov siab kawg (h 2 ) = 0 (puag ncig ntawm txoj kab)
Qhov ceev pib ntawm yam khoom (v 1 ) = 0 (thawj yam khoom nyob ntawm qhov chaw so)
Qhov ceev kawg ntawm yam khoom (v 2 ) = …. (qhov ceev ntawm yam khoom nyob rau hauv qab ntawm txoj kev = qhov ceev ntawm yam khoom ua ntej kev sib tsoo)
Kev nrawm vim lub ntiajteb txawj nqus (g) = 10 m/s
Lo lus nug: Qhov ceev ntawm txhua yam khoom tom qab kev sib tsoo
Lus teb:
Qhov ceev ntawm cov khoom ua ntej kev sib tsoo
Ua ntej, xam qhov ceev ntawm cov khoom ua ntej kev sib tsoo siv cov mis rau txoj cai ntawm kev txuag lub zog tshuab . Qhov ceev ntawm cov khoom ua ntej kev sib tsoo = qhov ceev ntawm cov khoom thaum nws mus txog hauv qab ntawm txoj kev = qhov ceev kawg ntawm cov khoom.
Lub zog kho tshuab pib = Lub zog kho tshuab kawg
Lub zog muaj peev xwm ntawm lub ntiajteb txawj nqus + lub zog Kinetic = Lub zog muaj peev xwm ntawm lub ntiajteb txawj nqus + lub zog Kinetic
mgh 1 + 1/2 mv 1 2 = mgh 2 + 1/2 mv 2 2
mgh 1 + 0 = 0 + 1/2 mv 2 2
mgh 1 = 1/2 mv 2 2
gh 1 = 1/2 v 2 2
2 gh 1 = v 2 2
2(10)(1/5) = v 2 2
2(2) = v 2 2
4 = v 2 2
v2 = √4
v2 = 2 m/ s
Qhov ceev ntawm txhua yam khoom ua ntej sib tsoo = 2 m//s.
Qhov ceev ntawm cov khoom tom qab kev sib tsoo
Xam qhov ceev ntawm cov khoom tom qab kev sib tsoo siv cov mis sib tsoo zoo kawg nkaus elastic.
Hauv kev sib tsoo uas ywj pheej zoo kawg nkaus, yog tias qhov hnyav ntawm ob yam khoom zoo ib yam thiab lawv cov kev txav mus los sib txawv, ces thaum lawv sib tsoo, ob yam khoom sib pauv qhov ceev. Piv txwv li, ua ntej kev sib tsoo, yam khoom A txav ntawm 2 m/s thiab yam khoom B txav ntawm -4 m/s. Tom qab kev sib tsoo, yam khoom A txav ntawm 4 m/s thiab yam khoom B txav ntawm -2 m/s. Cov cim tsis zoo thiab zoo qhia tias ob yam khoom nyob rau hauv kev taw qhia sib txawv.
Hauv lo lus nug no, qhov kev taw qhia ntawm kev txav mus los ua ntej kev sib tsoo yog qhov sib txawv thiab qhov ceev ntawm ob yam khoom ua ntej kev sib tsoo yog 2 m / s yog li qhov ceev ntawm ob yam khoom tom qab kev sib tsoo kuj yog 2 m / s, tab sis cov cim sib txawv, ib qho yog qhov zoo thiab lwm qhov yog qhov tsis zoo.
Cov lus teb yog C.
9. Saib daim duab hauv qab no!
Khoom A uas hnyav 2 kg thiab khoom B uas hnyav 3 kg raug tso tawm ntawm qhov chaw nruab nrab ntawm lub voj voog 1/4 tib lub sijhawm yam tsis muaj qhov ceev pib. Ob qho khoom hla dhau qhov chaw du thiab nkhaus thiab sib tsoo ntawm qhov chaw C hauv txoj kev ywj pheej zoo kawg nkaus (g = 10 ms -2 ). Qhov ceev ntawm cov khoom A thiab B tam sim ntawd tom qab sib tsoo yog…
A. -2 ms-1 thiab -2 ms-1
B. -3 ms -1 thiab 7 ms -1
C. -4 ms -1 thiab 7 ms -1
D. 4 ms -1 thiab -3 ms -1
E. 7 ms -1 thiab 3 ms -1
Kev Sib Tham
Nws paub tias:
Qhov hnyav ntawm yam khoom A (m1 ) = 2 kg
Qhov hnyav ntawm yam khoom B (m2 ) = 3 kg
Qhov siab pib (h 1 ) = 5 meters
Qhov siab kawg (h 2 ) = 0 (puag ncig ntawm txoj kab)
Qhov ceev pib ntawm yam khoom (v 1 ) = 0 (thawj yam khoom nyob ntawm qhov chaw so)
Qhov ceev kawg ntawm yam khoom (v 2 ) = …. (qhov ceev ntawm yam khoom nyob rau hauv qab ntawm txoj kev = qhov ceev ntawm yam khoom ua ntej kev sib tsoo)
Kev nrawm vim lub ntiajteb txawj nqus (g) = 10 m/s
Lo lus nug: Qhov ceev ntawm txhua yam khoom tom qab kev sib tsoo
Lus teb:
Qhov ceev ntawm cov khoom ua ntej kev sib tsoo
Ua ntej, xam qhov ceev ntawm yam khoom ua ntej kev sib tsoo siv txoj cai ntawm kev txuag lub zog tshuab . Qhov ceev ntawm yam khoom ua ntej kev sib tsoo = qhov ceev ntawm yam khoom thaum nws mus txog hauv qab ntawm txoj kev.
Lub zog kho tshuab pib = Lub zog kho tshuab kawg
Lub zog muaj peev xwm ntawm lub ntiajteb txawj nqus = lub zog Kinetic
mgh 1 = 1/2 mv 2 2
gh 1 = 1/2 v 2 2
2 gh 1 = v 2 2
2(10)(5) = v 2 2
100 = v2 2
v2 = √100
v2 = 10 m/ s
Qhov ceev ntawm txhua yam khoom ua ntej kev sib tsoo = 10 m/s. Qhov hnyav ntawm yam khoom tsis cuam tshuam rau qhov ceev kawg.
Qhov ceev ntawm cov khoom tom qab kev sib tsoo
Ob yam khoom muaj qhov hnyav sib txawv thiab txav mus rau hauv qhov sib txawv yog li qhov ceev ntawm txhua yam khoom tom qab kev sib tsoo raug suav los ntawm kev siv cov qauv no:
Qhov ceev ntawm txhua yam khoom tam sim ntawd tom qab kev sib tsoo:
10. Ob lub pob txhua lub muaj qhov hnyav m1 = 2 kg thiab m2 = 1 kg dov mus rau sab nraud nrog qhov ceev v1 = 2 ms-1 thiab v2 = 4 ms-1 zoo li nyob rau hauv daim duab hauv qab no. Ob lub pob ces sib tsoo thiab tom qab sib tsoo lawv lo ua ke. Kecepatan ob lub pob tom qab kev sib tsoo yog ...
A. 2 ms-1
B. 1,2 ms-1
C. 1 ms-1
D. 0,5 ms-1
E. xoom
Kev Sib Tham
Nws yog paub :
Qhov hnyav ntawm lub pob 1 (m1) = 2 kg
Qhov hnyav ntawm lub pob 2 (m2) = 1 kg
Qhov ceev ntawm lub pob 1 ua ntej kev sib tsoo (v1) = 2 m/s
Qhov ceev ntawm lub pob 2 ua ntej kev sib tsoo (v2) = -4 m/s
Qhov ceev yog qhov zoo thiab qhov tsis zoo vim tias qhov kev taw qhia ntawm lub pob txav mus rau sab nraud. Cov cim zoo thiab qhov tsis zoo qhia txog qhov kev taw qhia ntawm lub pob txav mus.
Nug : Qhov ceev ntawm lub pob tom qab sib tsoo (v')
Jawb :
Lo lus nug no muaj feem cuam tshuam nrog kev sib tsoo tsis sib luagHauv kev sib tsoo tsis sib xws, txoj cai ntawm kev txuag lub zog kinetic tsis siv thiab tsuas yog siv tau xwb txoj cai ntawm kev txuag lub zogQhov ceev ntawm lub pob tom qab kev sib tsoo yog suav los ntawm kev siv cov mis rau txoj cai ntawm kev txuag lub zog.
m1 v1 +m2 v2 = (m1 +m2) v'
(2)(2) + (1)(-4) = (2 + 1) v'
4 – 4 = (3) v'
0 = (3) v'
v' = 0
Cov lus teb yog yog E.
11. Ob lub pob A thiab B muaj tib lub cev hnyav thiab txav mus rau ib leeg ntawm qhov ceev ntawm 4 m/s.-1 thiab 6 ms-1 zoo li nyob rau hauv daim duab! Ob tug ceskev sib tsoo zoo kawg nkaus elastic, thiab qhov ceev ntawm yam khoom B tom qab kev sib tsoo yog 4 ms-1 nyob rau hauv qhov kev taw qhia rov qab ntawm nws thawj qhov kev txav mus los. Qhov ceev ntawm lub pob A tam sim ntawd tom qab kev sib tsoo yog ...
A. 2 ms-1
B. 2,5 ms-1
C. 4 ms-1
D. 5 ms-1
E. 6 ms-1
Kev Sib Tham
Nws yog paub :
Qhov hnyav ntawm lub pob A (mA) = m
Qhov hnyav ntawm lub pob B (mB) = m
Qhov ceev ntawm lub pob A ua ntej kev sib tsoo (v)A) = 4 m/s
Qhov ceev ntawm lub pob B ua ntej kev sib tsoo (v)B) = 6 m/s
Qhov ceev ntawm lub pob B tom qab kev sib tsoo (v)B') = 4 m/s
Nug : Qhov ceev ntawm lub pob A tom qab kev sib tsoo (vA')
Jawb :
Yog tias ob yam khoom uas sib tsoo elastically muaj tib qhov hnyav, ces tom qab kev sib tsoo ob yam khoom yuav pauv lawv qhov hnyav. qhov ceev.
Qhov ceev ntawm lub pob A ua ntej kev sib tsoo (v)A) = qhov ceev ntawm lub pob B tom qab sib tsoo (vB') = 4 m/s
Qhov ceev ntawm lub pob B ua ntej kev sib tsoo (v)B) = qhov ceev ntawm lub pob A tom qab sib tsoo (vA') = 6 m/s
Yog tias lub pob A txav mus rau sab laug ua ntej kev sib tsoo, tom qab ntawd tom qab kev sib tsoo, lub pob A txav mus rau sab xis. Ib yam li ntawd, yog tias lub pob B txav mus rau sab xis ua ntej kev sib tsoo, tom qab ntawd tom qab kev sib tsoo, lub pob B txav mus rau sab laug. Yog li, hauv kev sib tsoo zoo meej, qhov kev taw qhia ntawm kev txav mus los ntawm cov khoom ua ntej thiab tom qab kev sib tsoo yog qhov sib txawv.
Cov lus teb yog yog E.
12. Cov khoom A thiab B, txhua yam muaj qhov hnyav 4 kg thiab 5 kg, txav mus rau hauv cov kev taw qhia sib txawv raws li pom hauv daim duab. Ob qho tib si ces sib tsoo thiab tom qab sib tsoo, ob yam khoom tig rov qab nrog qhov ceev ntawm A = 4 ms.-1 thiab qhov ceev B = 2 ms-1, ces qhov ceev ntawm yam khoom B ua ntej kev sib tsoo yog...
A. 6,0 ms-1
B. 3,0 ms-1
C. 1,6 ms-1
D. 1,2 ms-1
E. 0,4 ms-1
Kev Sib Tham
Nws yog paub :
Qhov hnyav ntawm yam khoom A (mA) = 4 kg
Qhov hnyav ntawm yam khoom B (mB) = 5 kg
Qhov ceev ntawm yam khoom A ua ntej kev sib tsoo (v)A) = 6 m/s
Qhov ceev ntawm yam khoom A tom qab kev sib tsoo (v)A') = 4 m/s
Qhov ceev ntawm yam khoom B tom qab kev sib tsoo (v)B') = -2 m/s
Cov cim zoo thiab tsis zoo piav qhia txog qhov kev taw qhia ntawm lub pob.
Nug : Qhov ceev ntawm yam khoom B ua ntej kev sib tsoo (v)B)
Jawb :
Lo lus nug no tsis piav qhia txog hom kev sib tsoo. Txawm li cas los xij, raws li cov lej paub, nws tuaj yeem xaus lus tias lo lus nug no cuam tshuam nrog kev sib tsoo ib nrab elastic lossis kev sib tsoo tsis zoo elastic. kev sib tsoo ib nrab elastic Txoj cai ntawm kev txuag lub zog kinetic tsis siv tau thiab tsuas yog txoj cai ntawm kev txuag lub zog momentum xwb thiaj siv tau. Qhov ceev ntawm yam khoom B ua ntej kev sib tsoo yog suav los ntawm kev siv cov qauv ntawm txoj cai ntawm kev txuag lub zog momentum.
mA vA +mB vB = kuvA vA' + mB vB'
(4)(6)+(5)(-2) = (4)(4)+(5)(vB')
24 – 10 = 16 + 5(v)B')
14 – 16 = 5 (v)B')
-2 = 5 (v)B')
vB' = -2/5
vB' = -0,4
Lub cim tsis zoo txhais tau hais tias qhov kev taw qhia ntawm kev txav mus los ntawm yam khoom B tom qab kev sib tsoo yog qhov sib txawv rau qhov kev taw qhia ntawm yam khoom ua ntej kev sib tsoo.
Cov lus teb yog yog E.
Qhov chaw nug lus:
Cov Lus Nug Txog Kev Xeem Physics Hauv Tebchaws Rau Tsev Kawm Ntawv Theem Siab/Tsev Kawm Ntawv Theem Siab Ua Haujlwm
