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苏科版九年级上第11章第3节《功》,这节对功的定义,以及做功的必要条件作了详细而深刻的描述,即对物体做功的必要条件为:一是对物体要有力的作用,二是物体要在力的方向上通过一定的距离.为了巩固对做功的两个必要条件的理解,课本上特地例举了几种生活情景,判断人做功了吗?其中有一幅是学生背着书包在水平路面上匀速前进,如图1所示,由于学生背书包的力方向(竖直向上)与其水平路面匀速前进方向(水平方向)相互垂直,即书包没有在
Su Ke version of the ninth grade eleventh chapter section 3 “Gong”, this section of the definition of work, as well as the necessary conditions for the work made a detailed and profound description of the work done on the necessary conditions for the work: First, the object to Powerful role, the second is the object in the direction of force through a certain distance.In order to consolidate the understanding of the two necessary conditions for doing work, the textbook specifically enumerated several life scenarios, to judge people do it? One of them Is a student carrying a school bag in a uniform progress on the level of the road, as shown in Figure 1, due to the direction of the student endorsing bag force (vertical upward) and horizontal road surface uniform direction (horizontal direction) perpendicular to each other,