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minca2979
2 năm trước
Hãy chỉ ra nhận xét đúng trong các nhận xét sau: A. Chiếc cặp sách đặt trên bàn, ta nói bàn đã thực hiện một công cơ học để nâng cặp. B. Quả nặng treo dưới lò xo, ta nói lò xo đã thực hiện một công cơ học để giữ quả nặng. C. Quả táo rơi từ trên cây xuống đất, ta nói trọng lực đã thực hiện một công cơ học. D. Cả ba nhận xét A, B, C đều sai.
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