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1
(mỏng phẳng) có khối lợng 2kg và lò xo có độ cứng
k=100N/m đang dao động điều hoà trên mặt phẳng nằm ngang không ma sat với biên độ
A=5cm.Khi vật m
1
dến vị trí biên ngời ta đặt nhẹ lên nó một vật có khối lợng m
2
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ma sát giữa m
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