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urashimataro1810
2 năm trước
Một vật thực hiện dao động điều hoà với biên độ A tại thời điểm $t_{1}$ = 1,2s vật đang qua vị trí cân bằng theo chiều dương. Tại thời điểm $t_{2}$ = 4,7 s vật đang ở biên âm và đã đi qua vị trí cân bằng 3 lần tính từ thời điểm $t_{1}$ ( không tính lần ở $t_{1}$ ). Hỏi tại thời điểm ban đầu thì vật đang ở đâu và đi theo chiều nào ?
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