1、 1 ( ) ( 40 ) A 1 ) ( ) A B C D C A B C D 2 110 ( ) A B C D C A B D C 3 ) ( ) 92492214 A B C D A 2 A 4. A F F P ( ) A F P B F P C F P D F P A v0 A Fcos mg F C v v0cos F P Fv mgv0 P A B D 5 m t 0 F ( ) A t1 F F 2 2m t1 B t1 t1 F F 2 2m t 2 1 C t1 t1 F F 2 m t1 D t1 F F 2 m t 2 1 C t1 F W Fs F 1 2 F m
2、 t 2 1 F 2 t 2 1 2m F P W t1 F 2 t1 2m A D t1 v F m t1 t1 F P Fv F 2 t1 m B C 6 ( ) m v0 P 2 3 P 3 v t t1 0 t1 ( ) A t 0 2P 3mv0B C 5 18 mv 2 0 2 3 Pt1 D 2v0t1 3 5mv 3 0 18PBD f P v0 t 0 F 2P 3 v0 2P 3v0 a f F m P v0 2P 3v0 m P 3mv0 A 0 t1 P Fv B 2 3 Pt1 Wf 1 2 m 2 3 v0 2 1 2 mv 2 0 Wf 5 18 mv 2 0 2
3、 3 Pt1 C s Wf f 2v0t1 3 5mv 3 0 18P D B D. 7 v t 0 t1 t1 P P t3 v3 ( ) A 0 t3 B t2 t1 4 C t3 D P v3D 0 t1 t1 t3 A B t3 C f F P v3 D 8 m v1 P v2 h ( ) 92492215 A P v2B mg C P mgD P mv1 g D P v2 A B P mg C v1 F P v1 a F mg m P mv1 g D B P t f v t ( ) 5 A P1 P2 v1 v2 P1 fv1 P2 fv2 v1 P1 f v2 P2 f . t 0
4、 v0v1 t1 P1 P2 P Fv P2 v f ma2 a2 v a2 0 A C 10 ( ) O M N M N ONM OMN 2 . M N ( ) A B C D N M N BCD M N ONM OMN 2 M N M N 6 A B C M N N M N D 11 ( ) m m. P k g ( ) A B P 2kmgC v P 1 2 v P 3mv gk D 2 3 P BD P 2kmgv1 P 3kmgv 1.5 A P 2kmgv1 v1 P 2kmg B v 2 F 2P v f 3kmg a F f 3m 2P 3mv gk C P 3kmgv v P
5、 3kmg 2kmg 2kmgv 2 3 P D 12 l E0 k. 7 F 0 kl 2 kl 2 WF Fl 1 2 kl 2 n E nE0 1 2 kl 2 n kl 2 2E0 . kl 2 2E013 ) MD 2000 4 m 2.0 s 1 000 kg 90 kW 1 500 N. (1) (2) (3) (4) 3 000 N 2 400 m ( ). 92492216 (1) 1 2 s x1 9 m 2 2 s x2 15 m a x T 2 1.5 m/s 2 . (2) F Ff ma F Ff ma (1 500 3 000 N v P F 3 3m/s 30 m/s t1 v a 30 1.5s 20 s. 8 (3) vm P Ff 3 3m/s 60 m/s. (4) (1) (2) t1 20 s x1 vt1 2 30 2 300 m x2 (2 400 300)m 2 100 m P t2 Ffx2 1 2 m(v 2 m v 2 ) t2 50 s t t1 t2 (20 50)s 70 s. (1)1.5 m/s 2(2)20 s (3)60 m/s (4)70 s
