有一类这样的物理题,题中要求的量有一最大值,这个量受另两个量的影响,并且这两个量在一定程度上相互制约着,这样的习题用说理法往往很难论证,若使用求二次函数极值法或根的判别式,则可迎刃而解.例1:如图1物体体积为 V 物,密度为 p 物, There is a class of such physics questions. The quantity required in a question has a maximum value. This quantity is affected by the other two quantities, and these two quantities are mutually restricted to a certain extent. Such exercises are often difficult to argue with reasoning methods. If you use the quadratic function quadratic method or root discriminant, you can solve the problem. Example 1: As shown in Figure 1, the object volume is V and the density is p.