1、 - 1 - 01 1 2017 mB=2kg B mA=6kg A B mC=2kg C L=0.8m O C C A t=10 2 s C h=0.2m A B 1=0.2 B 2=0.1 g=10m/s 2 C A A B B mCgL=mCvC 2 C vC=4m/s C mCgh=0 mC C 2 C C=2m/s C F t= mC C mCvC C F=1200N A mCvC= mC C+mAvA A vA=2m/s A B B A B mAvA= mA+mB v - 2 - v=1.5m/s Agx=mAvA 2 mA+mB v 2 x=0.5m C A 1200N A B
2、B 0.5m 2 ) 1.80 m 80 kg 2.10 m 2.55 m 0.2 s (g 10 m/s 2 ) (1) (2) (2) (F mg)t mv 0 F mv t mg F 3N F 3N (1)3 m/s 3N 3 9 2016 - 3 - g 10m/s 2 ( ) m/kg 8.5 H/cm 45 h/cm 20 Fm/N 850 t/s 0.1 a b - 4 - 6 4 M m v0 F (1) (2) - 5 - (2) F t mv mv0 v mv0 M m t Mmv0 M m F (1) Mmv 2 0 2 M m Mmv 2 0 2F M m (2) Mm
3、v0 M m F5 2017 A B A 2m B 9m m vo A A A B i A A ii B B - 6 - 1 A 2 A B B 2 B B 6. m=0.5kg h=1m v0=7m/s H=3.046m 67/22m =0.01s g=10m/s 2 67 =8.2. i f ii F - 7 - ii F F-mg t=mv- -mv 2 F =815N 1 F= F =815N 7. P 50kg 20m g 10m/s 2 1 P 4s 2 k=100N/m F=kx x P m - 8 - 2 mg=kx x=5m P 20+5=25m 8 1.8m m=2kg 3.6m 1.0s 1.8m L= 1 2 gt12 t1 =0.6s - 9 - v1=gt1= v2 v2 t2 =1s- t1 =0.4s h= v2t2 + 1 2 gt22 h=3.6m-1.8m=1. 8m v2=2.5m/s I=mv2- mv1=-7N s 9 2016 A B mA=4.0kg mB=3.0kg. B . C t=0 t=4s A A C v-t . C mC B 4 s 12s B I B Ep - 10 -
