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Ngocngoc123
2 năm trước
Một con lắc đơn gồm sợi dây có chiều dài l = 1 m, vật nặng có khối lượng 100g. Kéo con lắc khỏi vị trí cân bằng thẳng đứng để dây lệch góc 45 0 so với phương thẳng đứng rồi thả nhẹ, bỏ qua mọi ma sát. Lấy g= 9,8m/s 2 . Lực căng của dây treo khi nó về qua vị trí dây treo lệch góc 30 độ là bao nhiêu ?
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