02-24
1、势能定义在相互作用力是“耗散力”(如摩擦力)时,设物体由A点(假设它是势能零点)移到B点克服它做功为W,当物体由B点回到A点时,它并不能对物体做功(如克服摩擦力做功时,物体的动能转化为内能,而无法利用这部分内能对物体做功),故...
07-21
WhatCanWeDofortheEnvironment?Ourenvironmentisbecomingworseandworse,sowhatcanwedofortheenvironment?Ithinkeachofuscandoalittlebittohelptosolvethisproblem。Thefirstthingwecandoistouseclothbagsinsteadofpla...