Một đầu máy xe lửa kéo 1 đoàn tàu chuyển động đều với vận tốc 54 km/h. Biết lực kéo của đầu máy là 5.10^5N. tính: a.Công suất của đầu tàu đó b.Công của đầu máy thực hiện khi chuyển động trên đoạn đường 12km

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