1. Ib lub pob A hnyav 200-gram, txav mus los ntawm qhov ceev 10 m/s, ntaus lub pob B hnyav 200-gram, thaum so. Qhov ceev ntawm lub pob A thiab lub pob B tom qab sib tsoo yog dab tsi?
Paub:
Qhov hnyav ntawm lub pob A (m A ) = 200 grams = 0.2 kg
Qhov hnyav ntawm lub pob B (mB ) = 200 grams = 0.2 kg
Qhov ceev ntawm lub pob A ua ntej sib tsoo (v A ) = 10 m/s
Qhov ceev ntawm lub pob B ua ntej sib tsoo (v B ) = 0
Xav tau: qhov ceev ntawm lub pob A (v A ') thiab qhov ceev ntawm lub pob B (v B ') tom qab kev sib tsoo
Tshuaj:
v A ' = v B = 0
vB ' = vA = 10 m/s
[irp]
2. Ob yam khoom uas muaj qhov hnyav sib npaug zos los ze rau ib leeg, sib tsoo thiab tom qab ntawd dhia tawm. Qhov ceev ntawm qhov hnyav A ua ntej sib tsoo yog 8 m/s thiab qhov ceev ntawm qhov hnyav B ua ntej sib tsoo yog 12 m/s. Qhov loj thiab qhov kev coj ntawm qhov ceev ntawm qhov hnyav A thiab qhov hnyav B tom qab sib tsoo yog dab tsi!
Paub:
Qhov hnyav A (m A ) = m
Qhov hnyav B (mB ) = m
Qhov ceev ntawm pawg A ua ntej sib tsoo (v A ) = -8 m/s
Qhov ceev ntawm pawg B ua ntej sib tsoo (v B ) = 12 m/s
Cov cim ntxiv thiab rho tawm qhia tias cov khoom txav mus rau sab nraud.
Xav tau: qhov loj thiab kev coj ntawm qhov ceev ntawm pawg A (v A ') thiab pawg B (v B ') tom qab kev sib tsoo
Tshuaj:
Hauv kev sib tsoo zoo kawg nkaus elastic, yog tias cov khoom muaj qhov hnyav sib npaug ces qhov ceev ntawm A tom qab kev sib tsoo (v A ') = qhov ceev ntawm B ua ntej kev sib tsoo (v B ) thiab qhov ceev ntawm B tom qab kev sib tsoo (v B ') = qhov ceev ntawm A ua ntej kev sib tsoo (v A ).
Yog tias ua ntej sib tsoo, A txav mus rau sab xis thiab B txav mus rau sab laug, ces, tom qab sib tsoo, A txav mus rau sab laug thiab B txav mus rau sab xis.
Cov khoom muaj qhov hnyav sib npaug thiab qhov kev sib tsoo yog elastic zoo kawg nkaus yog li ob qho khoom sib pauv qhov ceev.
v A ' = -v B = -12 m/s
vB ' = vA = 8 m/s
Cov cim ntxiv thiab rho tawm qhia tias cov khoom txav mus rau sab nraud.
[irp]
3. Ib yam khoom hnyav 2-kg, A, txav mus nrog qhov ceev 10 m/s, ntaus ib lub pob hnyav 4-kg, B, txav mus nrog qhov ceev 20 m/s. Yog tias qhov kev sib tsoo yog elastic zoo kawg nkaus, qhov ceev ntawm yam khoom A thiab yam khoom B yog dab tsi tom qab kev sib tsoo?
Paub:
Qhov hnyav A (mA ) = 2 kg
Qhov hnyav B (mB ) = 4 kg
Qhov ceev ntawm yam khoom A ua ntej sib tsoo (v A ) = 10 m/s
Qhov ceev ntawm yam khoom B ua ntej sib tsoo (v B ) = 20 m/s
Xav tau : qhov ceev ntawm yam khoom A (v A ') thiab qhov ceev ntawm yam khoom B (v B ') tom qab sib tsoo
Kev daws teeb meem :
Hauv kev sib tsoo zoo kawg nkaus elastic , yog tias cov khoom muaj qhov hnyav sib npaug thiab mus ze rau ib leeg, qhov ceev ntawm cov khoom tom qab sib tsoo raug suav los ntawm kev siv cov mis no:
Qhov ceev ntawm yam khoom A tom qab kev sib tsoo:
[irp]
4. Ib yam khoom hnyav 100-gram txav mus los ntawm 20 m/s tsoo ib phab ntsa uas sib tsoo tau zoo heev. Qhov loj thiab qhov kev coj ntawm qhov ceev ntawm yam khoom tom qab sib tsoo yog dab tsi.
Paub:
Qhov hnyav (mA ) = 100 grams = 0.1 kg
Qhov hnyav ntawm phab ntsa (mB ) = infinity
Qhov ceev ntawm pawg ua ntej sib tsoo (v A ) = 20 m/s
Qhov ceev ntawm pawg tom qab sib tsoo (v B ) = 0
Xav tau : qhov loj thiab kev coj ntawm qhov ceev tom qab sib tsoo
Tshuaj:
Yog tias v B = 0, m A me heev thiab m2 loj heev ces v A ' = -v A thiab v2 ' = 0.
Cov cim ntxiv thiab rho tawm qhia tias cov khoom txav mus rau sab nraud.
5. Ob lub pob, A nrog qhov hnyav ntawm 2-kg thiab pob B nrog qhov hnyav ntawm 5-kg, ua ntej thiab tom qab kev sib tsoo tau qhia nyob rau hauv daim duab hauv qab no. Yog tias kev sib tsoo yog elastic zoo kawg nkaus, qhov ceev ntawm lub pob A ua ntej kev sib tsoo yog dab tsi?
Paub:
Qhov hnyav ntawm lub pob Ib (mA) = 2 kg
Qhov hnyav ntawm lub pob B (mB ) = 5 kg
Qhov ceev ntawm lub pob B ua ntej sib tsoo (v B ) = 2 m/s
Qhov ceev ntawm lub pob A tom qab sib tsoo (v A ') = 5 m/s
Qhov ceev ntawm lub pob B tom qab sib tsoo (v B ') = 4 m/s
Ob lub pob txav mus rau sab xis yog li lawv qhov ceev kos npe zoo.
Xav tau: Qhov ceev ntawm lub pob A ua ntej sib tsoo (v A )
Tshuaj:
mA vA +mB vB = kuvA vA' + mB vB'
2(v A ) + (5)(2) = (2)(5) + (5)(4)
2(vA ) + 10 = 10 + 20
2(vA ) + 10 = 30
2(vA ) = 30 – 10
2(vA ) = 20
vA = 20/2
v A = 10 m/s
[irp]
6. Cov khoom A thiab B taug kev raws txoj kab rov tav, raws li pom hauv daim duab hauv qab no. Yog tias qhov kev sib tsoo yog qhov elastic zoo kawg nkaus thiab qhov ceev ntawm cov khoom B tom qab kev sib tsoo yog 15 m/s 1 , qhov ceev ntawm cov khoom A tom qab kev sib tsoo yog dab tsi.
Paub:
Qhov hnyav ntawm yam khoom Ib (mA) = 5 kg
Qhov hnyav ntawm yam khoom B (mB ) = 2 kg
Qhov ceev ntawm yam khoom A ua ntej sib tsoo (v A ) = 12 m/s
Qhov ceev ntawm yam khoom B ua ntej sib tsoo (v B ) = 10 m/s
Qhov ceev ntawm yam khoom B tom qab sib tsoo (v B ') = 15 m/s
Ob qho khoom, ua ntej thiab tom qab sib tsoo, txav mus rau sab xis kom lawv qhov ceev kos npe zoo.
Xav tau: Qhov ceev ntawm yam khoom A tom qab sib tsoo (v A ')
Tshuaj:
mA vA +mB vB = kuvA vA' + mB vB'
(5)(12) + (2)(10) = (5)v A ' + (2)(15)
60 + 20 = (5)v A ' + 30
80 = (5)v A ' + 30
80 – 30 = (5)v A '
50 = (5)v A '
v A ' = 50/5
v A ' = 10 m/s
[wpdm_package id='1156′]
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