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竞赛题如图1,一个滑轮重10N,工人的体重为600N,吊筐重80N,工人匀速吊起自己的时候所用的拉力的大小 F=____N.分析此题是求力的大小,因而要对物体进行受力分析,其中研究对象的选取尤为重要.研究对象的选取是否得当,直接影响着这个题目的难易程度.比如,此题第一问,求人所用的拉力,.研究对象可以选取单个的人,也可以把人和吊筐看成一个整体作为一个研究对象,还可以把人、吊筐和两个动滑轮看成一个整体作为研究对象,甚至还有其它情况.在此,我们就三种方法分别研究比较,达到理解选取研究对象的巧妙和重要.
Figure 1, a pulley weight 10N, the weight of workers is 600N, hanging basket weight 80N, workers pull their own uniform when the size of the pull force used F=____N. Analysis of this question is the size of the force, and therefore to The force analysis of the object, especially the selection of the research object. The proper choice of the research object directly affects the degree of difficulty of the topic. For example, the first question of this question asks people to use the pulling force, the research object can select a single The person can also regard the person and the hanging basket as a whole as a research object. He can also regard the person, the hanging basket and the two moving pulleys as a whole as the object of study. There are even other situations. Here we are three. The methods are studied and compared separately to achieve understanding and selection of the research object.