§3-5质点的动能定理和机械能守恒定律 1.质点的动能定理 MAL dv=F midt F·vdt=F.d dt dt vat=dr mydv=Fdr 2=d(vv)=(d)·v+v·dv=2vd d(mv)=fvdt= Fdr§3-5 质点的动能定理和机械能守恒定律 1.质点的动能定理 F t v m   = d d vdt r   = d F v t F r t v mv t       d d d d d  =  =  mv v F r     d = d v v v v v v v v v         d d( ) (d ) d 2 d 2 =  =  +  =  m v F v t F r     ) d d 2 1 d( 2 =  = 