物质的运动形式转变的过程中,或者物理现象、物理过程转变的过程中,存在着分界的现象,这就是常说的临界问题。物体处于这种转变状态,称为临界状态。要实现这种转变是有条件的,称为临界条件,有时是一个或几个物理量达到特殊值——临界值。例如物体在竖直平面内作圆周运动的临界速度,用电器的额定电 There is a phenomenon of demarcation in the course of the transformation of the form of movement of a material or in the process of the transformation of a physical phenomenon or a physical process. This is the often-critical issue. Objects in this transitional state are called critical states. To achieve this transition is conditional, known as a critical condition, and sometimes one or more physical quantities reach a special value, the critical value. For example, the critical speed of circular motion of an object in the vertical plane, the rated current of the appliance