5 Piv txwv ntawm kev sib tsoo tsis sib xws
1. Ib lub mos txwv uas hnyav 30 grams txav mus rau qhov ceev 30 m/s ntaus ib lub thaiv ntoo uas hnyav 1 kg uas tseem so. Txheeb xyuas qhov ceev ntawm lub thaiv yog tias lub mos txwv nyob hauv lub thaiv!
Kev Sib Tham
Nws yog paub :
Qhov hnyav ntawm lub mos txwv (m1) = 30 grams = 0,03 kg
Qhov hnyav ntawm lub block (m)2) = 1 kg
Qhov ceev pib ntawm lub mos txwv (v)1) = 30 m/s
Qhov ceev pib ntawm lub thaiv (v2) = 0 (lub thaiv ruaj khov)
Nug : qhov ceev ntawm lub mos txwv thiab thaiv tom qab kev sib tsoo (v')
Jawb :
Cov mis txoj cai ntawm kev txuag lub zog yog tias ob yam khoom lo ua ke tom qab sib tsoo:
m1 v1 +m2 v2 = (m1 +m2) v'
(0,03)(30) + (1)(0) = (0,03 + 1) v'
0,9 + 0 = 1,03 v'
0,9 = 1,03 v'
v' = 0,9 / 1,03
v' = 0,87 m/s
Qhov ceev ntawm lub mos txwv thiab lub thaiv tom qab kev sib tsoo yog 0,87 m / s.
2. Cov khoom A thiab B txhua tus muaj qhov hnyav ntawm 2 kg thiab txav mus rau ib leeg ntawm qhov ceev ntawm v.A = 6 ms-1 thiab vB = 4 ms-1Yog tias ob yam khoom kev sib tsoo tsis sib luag kiag li, ces qhov ceev ntawm ob yam khoom tom qab kev sib tsoo yog ...
Kev Sib Tham
Nws yog paub :
Qhov hnyav ntawm yam khoom A (mA) = 2 kg
Qhov hnyav ntawm yam khoom B (mB) = 2 kg
Qhov ceev pib ntawm yam khoom A (v)A) = -6 m/s
Qhov ceev pib ntawm yam khoom B (vB) = 4 m/s
Nug : qhov ceev ntawm ob yam khoom tom qab kev sib tsoo (v')
Jawb :
mA vA +mB vB = (mA' + mB) v'
(2)(-6) + (2)(4) = (2 + 2) v'
-12 + 8 = 4 v'
-4 = 4 v'
v' = -4 / 4
v' = -1 m/s
Qhov ceev ntawm ob yam khoom tom qab kev sib tsoo yog 1 m/s.
3. Ob yam khoom txhua yam muaj qhov hnyav m1 = 3 kg thiab m2 = 4 kg txav mus rau hauv kev taw qhia sib txawv ntawm qhov ceev v1 = 10 m/s thiab v2 = 12 m/s. Ob yam khoom sib tsoo thiab tom qab sib tsoo lawv lo ua ke. Qhov ceev ntawm ob yam khoom tom qab sib tsoo yog...
Kev Sib Tham
Nws yog paub :
Qhov hnyav ntawm yam khoom 1 (m1) = 3 kg
Qhov hnyav ntawm yam khoom 2 (m2) = 4 kg
Qhov ceev ntawm yam khoom 1 (v1) = -10 m/s
Qhov ceev ntawm yam khoom 2 (v2) = 12 m/s
Nug : qhov ceev ob yam khoom tom qab kev sib tsoo (v')
Jawb :
m1 v1 +m2 v2 = (m1' + m2) v'
(3)(-10) + (4)(12) = (3 + 4) v'
-30 + 48 = 7 v'
18 = 7 v'
v' = 18 / 7
v' = 2,6 m/s
Qhov ceev ntawm ob yam khoom tom qab kev sib tsoo yog 2,6 m/s.
4. Lub tsheb sedan uas raug nres tau raug lub tsheb npav tsoo nrog lub tsheb khiav ceev 36 km/teev. Tom qab muaj kev sib tsoo, lub tsheb sedan thiab lub tsheb npav tau sib tsoo. Yog tias lub tsheb npav hnyav 2000 kg thiab lub tsheb sedan hnyav 1000 kg, qhov ceev ntawm ob lub tsheb tom qab muaj kev sib tsoo yog dab tsi?
A. 3,45 m/s
B. 4,67 m/s
C. 5,45 m/s
D. 6,67 m/s
E. 7,67 m/s
Kev Sib Tham:
Nws yog paub tias :
v tsheb npav = 36 km/h = 36000 m/3600 s = 10 m/s
m tsheb npav = 2000 kg
v lub tsheb thauj khoom = 0
m lub tsheb thauj khoom = 1000 kg
Nug :
Qhov ceev ntawm lub tsheb sedan thiab lub tsheb npav tom qab kev sib tsoo (v')?
Lus teb :
m 1 v 1 + m 2 v 2 = (m 1 + m 2 ) v'
(2000)(10) + (1000)(0) = (2000 + 1000) v'
20.000 = 3000 v'
v' = 20.000 / 3000 = 6,67 m/s
Cov lus teb yog D.
5. Ib lub mos txwv hnyav 20 gram txav mus rau qhov ceev ntawm 100 m/s ntaus ib daim ntoo uas tsis txav thiab nkag mus rau hauv. Yog tias qhov hnyav ntawm daim ntoo yog 500 grams, qhov ceev ntawm daim ntoo thiab lub mos txwv tam sim ntawd tom qab sib tsoo yog dab tsi?
A. 1,50 m/s
B. 2,55 m/s
C. 3,85 m/s
D. 4,75 m/s
E. 5,65 m/s
Kev Sib Tham:
Nws yog paub tias :
m mos txwv = 20 grams = 0,02 kg
v mos txwv = 100 m/s
m thaiv = 500 grams = 0,5 kg
v thaiv = 0
Nug :
Qhov ceev ntawm lub mos txwv thiab thaiv tam sim ntawd tom qab kev sib tsoo (v')?
Lus teb :
m 1 v 1 + m 2 v 2 = (m 1 + m 2 ) v'
(0,02)(100) + (0,5)(0) = (0,02 + 0,5) v'
2 + 0 = 0,52 v'
2 = 0,52 v'
v' = 2 / 0,52 = 3,85 m/s
Cov lus teb yog C.
