1、 1 2 1 1 (1) (2) 2 3. (1) ( ) ( ) (2) (3) (4) v T v x t . 2 1 x y 2 2 3 ( ) 3 1 2. 1. T v T . 2 (1) nT( ) (2) (n (2n 1) 2 (n (3) 3 1 ) S 20 Hz 16 m/s. P Q S P Q S P Q S 15.8 m 14.6 m P Q ( ) A P Q B P Q C S P Q D S P E S Q BDE v f 16 20m 0.8 m P Q S PS 15.8 m 19 3 4 SQ 14.6 m 18 1 4 . P Q A B S P Q
2、S P Q C D E 2 ) x t 0 P x 3 m 2 0.4 s ( ) 92492422 A 4 m/s B 1.25 Hz C x 15 m t 0.6 s D x 22 m t 0.2 s E P x 17 m BDE 2 0.4 s 1 2 T 0.4 s T 0.8 s 4 m v T 5 m/s A f 1 T 4 1.25 Hz B x 15 m x 3 m 12 m x 3 m t 0.6 s x 15 m t 0.6 s C x 22 m x 2 m x 2 m t 0.2 s x 22 m t 0.2 s D x 17 m x 1 m P 1 m E x (1)
3、(2) (3) (4) (1) (2) (3) (4) 5 t 2 s (b) x 1.5 m P x 2 m ( ) A 0.5 m/s B C 0 2 s P 8 cm D 0 2 s P y E t 7 s P ACE (a) 2.0 m (b) T 4 s v T 0.5 m/s A (a) t 2 s (b) x 1.5 m t 2 s B 0 2 s P s 2A 8 cm C D t 7 s P 7 4 P t 3 4 T 3 s E x t 0.1 s x 2 m a t 0 ( ) 6 A 0.10 s B x C t 0.05 s a D t 0.10 s t 0.25 s
4、 a 40 cm E t 0.25 s x 4 m b y BCE T 0.2 s A t 0.1 s a x B a t 0.05 s C t 0.10 s t 0.25 s a t 0.25 0.1 0.2 T 3 4 T 3A 60 cm D T 0.2 s a t 0.25 s t 0.05 s y a b b y E 1 x t 2 3 4 1. (1) t T t T x x (2) 7 (3) 2 t x t nT t(n 0,1,2 x x(n 0,1,2 x x s A B A B t B A B (1) 2 s t T 4 v1 T 2s 4t s 2t . t 3T 4
5、v2 T 2s 4t 3 3s 2t . (2) s t 3T 4 v1 T 3s 4t t T 4 v2 T s 4t . (3) s t T 4 v1 T s 4t t 3T 4 v2 T 3s 4t . (4) 2 3 s t 3T 4 v1 T s 2t t T 4 v2 T s 6t 8 5 s 2t 3s 2t 3s 4t s 4t s 6t . 8 1 1 x x 12 m x 18 m ( ) A 12 s B x 12 m x 18 m C 0 4 s x 12 m x 18 m 6 cm D 8 m E 2 m/s ABD 12 s A x 12 m x 18 m B x
6、18 m y 4sin 6 t 0 4 s (8 2 3)cm C n 3 4 6 m n 0 8 m D v T 6 n 3 4 m/s 1 2n 3 2m/s n 2 m/s E 2 2 ) x t P t 0.6 s a b c P Q ( ) 92492423 9 A 50 m/s B a 30 cm C c 60 cm D T 0.8 s t 0.5 s b P E T 0.8 s t 0.4 s c x t(m) ACD 40 m 0.6 s nT 3 4 T(n 0,1,2 T 2.4 4n 3 s(n 0,1,2 n 0 T 0.8 s v T 50 m/s A x a t n
7、 0 T 0.8 s a 30 cm n 1 T 24 70s a 30 cm B n 1 T 24 70s c 1 4 T,0.6 s 7T 4 c 7 4 T 1 4 T 6 4 T c 6A 60 cm C T 0.8 s t 0.5 s b P D T 0.8 s t 0.4 s c y 0.1cos 5 2 t(m) E 3 3 0.2 s (1) (2) (1) t 3 4 T nT(n 0,1,2 10 T t 4n 3 0.2 4n 3s 0.8 4n 3s(n 0,1,2 Tm 0.8 3 (2) t T 4 nT(n 0,1,2 T 0.8 4n 1s(n 0,1,2 4
8、m v T 5(4n 1)m/s(n 0,1,2 (1) 0.8 4n 3 (n 0,1,2 0.27 s (2)5(4n 1)m/s(n 0,1,2 (1) (2) (3) v x t v T 1. (1) r. r (n 0,1,2 r (2n 1) 2 (n 0,1,2 ) r (2n 1) 2 (n 0,1,2 r (n (2) ( ) 11 2 (1) (2) 1. S1 S2 ( ) ( ) S1 A1 4 cm S2 A2 3 cm ( ) A D B A D 14 cm C B C D C 1 cm E C BDE D A A D AD 14 cm B A D B C C C 1 cm D C E 2 ( ) A B C D E ACE A B C D E
