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hathuhuyenmy
2 năm trước
Kéo vật nặng 100kg lên cao bằng mặt phẳng nghiêng dài 7m với lực kéo 500N;. biết mặt phẳng nghiêng có hiệu suất 75%. Tính: a/ Công của lực kéo? b/ Công có ích khi nâng vật c/ Chiều cao mặt phẳng nghiêng ? d. Độ lớn lực ma sát?
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