杠杆平衡原理:在均匀线段AB两端分别放置质量为m1千克、m2千克的物体,线段AB上的平衡点为O点,|AO|=l1,|BO|=l2,则m1l1=m2l2.若A(x1,y1),B(x2,y2),则点O可看作线段AB上的一个内分点,点O分有向线段AB所成的比λ=ll21=mm12,设O(x,y),则x=x11++λλx2,y=y11++λλy2,即x=m1mx11++mm Lever balance principle: Place mass m1 kilograms and m2 kilograms at both ends of the uniform line segment AB. The equilibrium point on the line segment AB is O point, |AO|=l1, |BO|=l2, then m1l1=m2l2. A(x1,y1),B(x2,y2), then point O can be regarded as an inner point on line AB, point O is divided into direction line AB and the ratio λ=ll21=mm12, set O(x) ,y), then x=x11++λλx2,y=y11++λλy2, ie x=m1mx11++mm