认清轻绳的力学特征,对正确分析物理现象和过程,建立物理模型,形成解题策略具有十分重要的作用。轻绳具有柔软、无质量、不可形变的特征.从受力本身看,轻绳所产生的拉力总是沿绳的方向,对绳两头被约束的物体产生作用改变其运动状态。从做功的角度看,由于所约束的情景不同,可能做功,也可能不做功。从拉力的时间积累效应看,有拉力的“缓变”与“突变”两种形式,不同的变化方式,使系统的机械能转变,产生不同的效果。 1 拉力的突变。导致被约束物体的运动状态发生突变 Recognizing the mechanical characteristics of light ropes plays an important role in correctly analyzing physical phenomena and processes, establishing physical models, and developing problem solving strategies. The light rope has a soft, massless, non-deformable characteristic. From the stress itself, the pulling force generated by the light rope is always in the direction of the rope and acts on the restrained objects at both ends of the rope to change its state of motion. From the perspective of doing work, due to the different scenarios constrained, it may or may not work. From the time accumulation effect of tension force, there are two forms of “stretching” and “abrupt change” of tension. Different ways of change will change the mechanical energy of the system and produce different results. 1 The mutation of tension. Causes mutations in the motion state of the constrained object