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在期中考试中,有道求机械效率的考题,学生出现多种错误,现解析如下。题目如图1所示,用滑轮组拉着重600N的物体A沿水平方向匀速移动,在40S内物体移动了8m,拉力F做的功为1280J。求(1)拉力, 的大小及拉力的功率;(2)若动滑轮的重力为12N(不计绳
In the mid-term exam, there were many questions that asked for mechanical efficiency. The students had a variety of mistakes. The analysis is as follows. As shown in Figure 1, the object A with a weight of 600N is pulled along the horizontal direction by a pulley block and moves at a constant speed in the horizontal direction. The object has moved 8m within 40s, and the work done by the pulling force F is 1280J. Find (1) Pull, size and pull power; (2) If the gravity of the moving pulley is 12N (do not count the rope