1、 1 1 ( ) A B C D 5 m/s 2 D A B C 5 m/s 2 mg F ma F D 2 4 4 11 m v0 P ( )( ) 4 4 11 A. 1 2 mv 2 0 mgh B. 1 2 mv 2 0 mgh C. 1 2 mv 2 0 D. 1 2 mv 2 0 mg(H h) C E0 Ek 1 2 mv 2 0. 3 m v0 v0 4 ( )( ) A. 15 32 mv 2 0 B. 17 32 mv 2 0 C. 1 32 mv 2 0 D. 4 9 mv 2 0 A 1 2 mv 2 0 Ep 1 2 m v0 4 2 Ep 15 32 mv 2 0.
2、 2 4 4 12 4 4 4 12 l1 l2 (l1 l2) A B ( ) ( ) A B B A C D A B A B A mgl2 1 2 mv 2 A EP EP B mgl2 1 2 mv 2 B vA vB A BCD 5 ( ) A B C D 4 5 g AC A C 4 5 g F mg m( 4 5 g) F 1 5 mg 1 5 mg 6 4 4 13 ( ) 4 4 13 A (a) B (b) C (c) ( ) D (c) 3 AC 4 4 14 7 4 4 14 A B O O ( ) A B B A C A D A B AC O mB mA A B A B
3、 B A 0 8 m 2m A B. 2l l O 4 4 15 OA ( ) 4 4 15 A A 2 gl B A C A D A B vA vB 1 2 BC vA vB ( l) ( l) 2 1 B D OA mg2lcos 2mgl(1 sin ) 1 2 mv 2 B 1 2 mv 2 A v 2 A 3 8 mgl(sin cos ) 8 3 mgl. sin cos C 4 4 16 4 9 (1) 4 4 16 k 4 kg 5 m/s _ (2) H 2 _ ( ) (3) 10 m/s 15 m _m/s(g 10 m/s 2 ) (1)50 J (2) H 3(3)20 10 4 4 17 2 m a 25.2 km/h 4 4 17 (1) a (2) b (g 10 m/s 2 ) (1) (2)3 m/s (1) a a E1 Ek1 1 2 mv 2 1 v1 25.2 km/h 7 m/s mgh 1 2 mv 2 1 h v 2 1 2g 7 2 m 2.45 m h h (2) b v2 1 2 mv 2 1 mgh 1 2 mv 2 2 v2 v 2 1 2gh 7 2 m/s 3 m/s.
