3 Piv txwv ntawm kev sib tsoo ib nrab elastic
1. Ib yam khoom hnyav 500-gram txav mus rau qhov ceev ntawm 10 m/s thiab ib yam khoom hnyav 200-gram txav mus rau qhov ceev ntawm 12 m/s. Ob yam khoom txav mus rau ib leeg thiab sib tsoo. Yog tias tom qab kev sib tsoo, qhov ceev ntawm yam khoom hnyav 500-gram yog 6 m/s, ces qhov ceev ntawm yam khoom hnyav 200-gram yog...
Kev Sib Tham
Nws yog paub :
Qhov hnyav ntawm yam khoom 1 (m1) = 500 grams = 0,5 kg
Qhov hnyav ntawm yam khoom 2 (m2) = 200 grams = 0,2 kg
Qhov ceev pib ntawm yam khoom 1 (v1) = -10 m/s
Qhov ceev pib ntawm yam khoom 2 (v2) = 12 m/s
Qhov ceev kawg ntawm yam khoom 1 (v1') = 6 m/s
v1 lub cim tsis zoo thiab v2 yog qhov zoo vim tias qhov kev taw qhia ntawm ob yam khoom yog qhov sib txawv.
Nug : qhov ceev kawg ntawm yam khoom 2 (v2')
Jawb :
Hauv kev sib tsoo tsis zoo ntawm elastic, aka kev sib tsoo ib nrab elastic, txoj cai ntawm kev txuag lub zog kinetic tsis siv thiab tsuas yog txoj cai ntawm kev txuag lub zog siv tau.
m1 v1 +m2 v2 = kuv1 v1' + m2 v2'
(0,5)(-10)+(0,2)(12) = (0,5)(6)+(0,2)(v2')
-5 + 2,4 = 3 + 0,2 v2'
-2,6 = 3 + 0,2 v2'
-2,6 – 3 = 0,2 v2'
-5,6 = 0,2 v2'
v2' = -5,6 / 0,2
v2' = -28 m/s
Qhov ceev ntawm yam khoom 2 tom qab kev sib tsoo (v2') yog 28 m/s.
v1' yog qhov zoo thiab v2' yog qhov tsis zoo vim tias tom qab kev sib tsoo, cov kev taw qhia ntawm ob yam khoom yog qhov sib txawv. Cov cim tsis zoo thiab cov cim zoo tsuas yog qhia tias ob yam khoom txav mus rau qhov sib txawv.
2. Ob yam khoom uas muaj tib lub cev loj txav mus rau ib leeg ua ib txoj kab ncaj, qhov twg qhov ceev ntawm yam khoom 1 yog 6 m/s thiab qhov ceev ntawm yam khoom 2 yog 8 m/s. Yog tias tom qab kev sib tsoo, yam khoom 2 txav mus rau sab laug ntawm qhov ceev ntawm 5 m/s, ces qhov loj thiab kev coj ntawm qhov ceev ntawm yam khoom 1 tom qab kev sib tsoo yog...
Kev Sib Tham
Nws yog paub :
Qhov hnyav ntawm yam khoom 1 (m1) = m
Qhov hnyav ntawm yam khoom 2 (m2) = m
Qhov ceev pib ntawm yam khoom 1 (v1) = -6 m/s
Qhov ceev pib ntawm yam khoom 2 (v2) = 8 m/s
Qhov ceev kawg ntawm yam khoom 2 (v2') = 5 m/s
Nug : qhov loj thiab kev coj ntawm qhov ceev ntawm yam khoom 1 tom qab kev sib tsoo
Jawb :
Cov qauv rau txoj cai ntawm kev txuag lub zog :
m1 v1 +m2 v2 = kuv1 v1' + m2 v2'
mv1 + mv2 = mv1' + mv2'
m (v)1 +v2) = m(v)1' + v2')
Qhov hnyav ntawm ob yam khoom yog tib yam yog li m raug tshem tawm ntawm qhov sib npaug:
v1 +v2 = v1' + v2'
-6 + 8 = v1' + 5
2 – 5 = v1'
v1' = -3 m/s
Qhov ceev ntawm yam khoom 1 tom qab kev sib tsoo (v1') yog 3 m/s. Lub cim tsis zoo qhia tias qhov kev taw qhia ntawm kev txav ntawm yam khoom 1 yog qhov sib txawv ntawm qhov kev taw qhia ntawm kev txav ntawm yam khoom 2. Yog tias tom qab kev sib tsoo yam khoom 2 txav mus rau sab xis, ces yam khoom 1 txav mus rau sab laug. Ib yam li ntawd, yog tias ua ntej kev sib tsoo yam khoom 2 txav mus rau sab laug, ces yam khoom 1 txav mus rau sab xis.
3. Lub pob 1 uas hnyav 1 kg thiab lub pob 2 uas hnyav 2 kg txav mus rau tib qho kev taw qhia thiab sib tsoo hauv ib txoj kev ywj pheej. Ua ntej sib tsoo, lub pob 1 txav ntawm qhov ceev ntawm 10 m/s thiab lub pob 2 txav ntawm qhov ceev ntawm 5 m/s. Txheeb xyuas qhov ceev ntawm lub pob 1 tom qab sib tsoo yog tias qhov ceev ntawm lub pob 2 tom qab sib tsoo yog 4 m/s.
Kev Sib Tham
Nws yog paub :
Qhov hnyav ntawm lub pob 1 (m1) = 1 kg
Qhov hnyav ntawm lub pob 2 (m2) = 2 kg
Qhov ceev pib ntawm lub pob 1 (v1) = 10 m/s
Qhov ceev pib ntawm lub pob 2 (v2) = 5 m/s
Qhov ceev kawg ntawm lub pob 2 (v2') = 4 m/s
Ob yam khoom txav mus rau tib qho kev taw qhia kom qhov ceev muaj tib lub cim (xaiv qhov zoo).
Nug : qhov ceev kawg ntawm lub pob 1 (v1')
Jawb :
m1 v1 +m2 v2 = kuv1 v1' + m2 v2'
(1)(10) + (2)(5) = (1)(v)1') + (2)(4)
10 + 10 = v1' + 8
20 – 8 = v1'
v1' = 12 m/s
Qhov ceev ntawm lub pob 1 tom qab kev sib tsoo yog 12 m/s.
