1 VIẾT PHƯƠNG TRÌNH DAO ĐỘNG ĐIỀU HÒA x = Acos(t + ) Phương pháp:   Để tìm ω ta có thể dùng các công thức sau:     2 T (s)     2 1  T f (Hz)  Để tìm A ta có thể dùng các công thức sau :   : Av . max     : Aa . 2 max     : L = 2.A   0  0.   0  0   2 2 22  v xA  ; 2 2 4 2 2  va A   Để tìm φ:  x x(t 0) A.cos cos A v(1 0) A. .sin v(1 0) A. .sin                           2 BÀI TẬP VẬN DỤNG Bài 1: t +    A.   rad. B.    rad. C.    rad. D.   rad. Bài 2:    A.    ) cm. B.    ) cm. C.    ) cm. D.    ) cm. Bài 3:   A. x = -12sin2t cm. B. x = 12sin2t cm. C. x = 12sin(2t + ) cm. D. x = 12cos2t cm. Bài 4:    A. x = -6cos4t cm. B. x = 6sin4t cm. C. x = 6sin(4t -   ) cm. D. x = 6cos4t cm. Bài 5:    A.  B.  C.    ) cm. D. -   ) cm. Bài 6:    A.  B.  C.    ) cm. D. -   ) cm. Bài 7:       A. x = 6co   ) cm. B. -   ) cm. C.  D.  Bài 8:    A.  B.    ) cm. C.    ) cm. D. -   ) cm. 3 Bài 9:     A.  B.    ) cm. C.    ) cm. D.    ) cm. Bài 10:    A. x = 5     ) cm B.    ) cm C.    ) cm D. x = 5     ) cm Bài 11:    A. x = 5     ) cm B. x = 5.cos 4 t + cm. 2      C. x = 10.cos 4 t + cm. 3      D. x = 5 2.cos 4 t cm. 4      Bài 12:   50 3 cm/s  A. x = 5  cos10t cm. B. x = 10cos     cm. C. x = 10cos     cm. D. x =   cos     cm. Bài 13:  =  50 3 cm/s  A. x = 5  cos    cm. B. x = 10cos     cm. C. x = 10cos     cm. D. x =   cos     cm. Bài 14:   -  A. x = 2 2cos(5t +   ) cm. B. x = 2cos (5t -   ) cm. C. x = 2cos(5t +   ) cm. D. x = 2 2cos(5t +   ) cm. Bài 15:   50 3 cm/s   A. x = 10cos     cm. B. x = 10cos     cm. C. x = 10cos     cm. D. x =   cos     cm. Bài 16:  = 5 3  A. x = 10cos     cm. B. x = 10cos     cm. 4 C. x = 10cos     cm. D. x =   cos     cm. Bài 17:   2    A. x = 10cos(10t -   ) cm. B. x = 5cos(20t -   ) cm. C. x = 10cos(10t) cm. D. x = 10cos(10t + ) cm. Bài 18:   2   M 0  0 = 5  A. x 10cos 2 t 4        cm. B. x = 5  cos(    ) cm. C. x = 10cos(    ) cm. D. x = 10cos(    ) cm. Bài 19:    A. x = 10cos(2t +   ) cm. B. x = 10cos(4t +   ) cm. C. x = 20cos(4t +   ) cm. D. x = 10cos(4t +   ) cm. Bài 20:       A. x = 5cos(2t -   ) cm. B. x = 5cos(2t + ) cm. C. x = 10cos(t -   ) cm. D. x = 5cos(t +   ) cm. Bài 21:  5 10  A.    ) cm. B.    ) cm. C. x 10cos 2 t 4        cm. D. -   ) cm. Bài 22:  A. x = 5cos(4t) cm. B. x = 5cos(2t - ) cm. C. x =5cos(4t +   ) cm. D. x = 5cos(t) cm. Bài 23:   A. x = 10cos(50t +   ) cm. B.    ) cm. C. x = 10cos(20t +   ) cm. 2  2 2 2 5 D. x = 10cos(100t -   ) cm. Bài 24:   A. x = 10cos(2t) cm. B. x = 10cos(2t +   ) cm. C. x = 10cos(2t    )cm. D. x = 10cos(2t + ) cm. Bài 25:                  x = Acos(t + A. v = Asin(t) cm/s. B. v = Asin(t +   ) cm/s. C. v = Asin(t +   ) cm/s. D. v = Asin(t -   ) cm/s. Bài 26:  A. x = 5cos(2t -   ) cm. B. x = 5cos(2t +   ) cm. C. x =5cos(t +   ) cm. D. x = 5cos(t -   ) cm. Bài 27:   A. x = 4cos(2t - 2 3 ) cm B. x = 4cos(2t + 2 3 ) cm C. x = 4cos(t - 2 3 ) cm D. x = 4cos(t + 2 3 ) cm Bài 28:       -       A. x = 50cos(5t +   ) cm. B. x = 10cos(5t +   ) cm. C. x = 10cos(5t -   ) cm. D. x = 10cos(5t -   ) cm. Bài 29:   A. x = 8cos(t) cm. B. x = 4cos(2t -   ) cm. C. x = 8cos(t -   ) cm. D. x = 4cos(2t +   ) cm. 6 Bài 30:   A. x = 8cos(t) cm. B. x = 4cos(2t -  2 ) cm. C. x = 8cos(t -  2 ) cm. D. x = 4cos(2t +  2 ) cm. Bài 31:   A.        cm. B.        cm. C.        cm. D.        cm. Bài 32:     = 10. A. x = 4cos     B. x = 4cos     C. x = 8cos     D. x = 8cos     Bài 33:  -.   A. v = - B.  C.    ) cm/s. D. v = -  1 640 v 16 x 22  2  )( 2 s m a t(s) 2 O 1 2 . 1 VIẾT PHƯƠNG TRÌNH DAO ĐỘNG ĐIỀU HÒA x = Acos(t + ) Phương pháp:   Để tìm ω ta