... x = 6cos(5t + /6)cm (1) a .Trong khong thi gian 2,5s vt qua v trớ x = 3cm my ln b .Trong khong thi gian 2s vt qua v trớ x = 4cm theo chiu dng my ln c .Trong khong thi gian 2,5s vt qua v trớ cõn ... ng bng 0,5 A B Sau thi gian , vt i c qung ng bng A T C Sau thi gian , vt i c qung ng bng A D Sau thi gian T, vt i c qung ng bng 4A A Sau thi gian Cõu 20(C2009): Mt cht im dao ng iu hũa cú phng ... mt khong thi gian t t1 n t2 ta thc hin cỏc bc sau : Vit phng trỡnh dao ng Tớnh khong thi gian t = t2 t1 so sỏnh vi chu k dao ng T (Chỳ ý cỏc trng hp c bit) Thit lp biu thc: t = nT + Trong ú...