工程力学双语课件ch05-Equilibrium-of-a-rigid-body

上或减去任意一个平衡力系,并不改变原力系对刚体的作用。2ndPrinciple:additionandsubtractionofbalancedforcesystems公理2加减平衡力系原理Corollary1:transmissibilityofaforceThepointofapplicationofaforceactingonarigidbodycanbetransferredtoanyotherpointonthelineofactionoftheforcewithoutalteringitseffect.推论1:力的可传性。作用于刚体上的力可沿其作用线移到同一刚体内的任一点,而不改变该力对刚体的效应。8因此,对刚体来说,力作用三要素为:大小,方向,作用线Therefore,asfarasarigidbodyisconcerned,aforcecanbecharacterizedbythreeelements:magnitude,directionandlineofapplication.2ndPrinciple:additionandsubtractionofbalancedforcesystems公理2加减平衡力系原理93rdprinciple:thelawofparallelogram公理3力的平行四边形法则Twoforcesappliedatonepointofabodyhaveastheirresultantaforceappliedatthesamepointandrepresentedbythediagonalofaparallelogramconstructedwithtwogivenforcesasitssides.作用于物体上同一点的两个力可合成一个合力,此合力也作用于该点,合力的大小和方向由以原两力矢为邻边所构成的平行四边形的对角线来表示。10