aB EⅣxH=HⅣ×EVE×H=-H V·(E×H at aD aB E H ⅴE×H) at dt E·Ja aD aB E·一+H -(E×Hc2 at at ow D aB E·+H E×H at at at w=wdV dt =IE Jdv=fvdr =-m-s△=5-S△ 机动目录 页返回结束( ) ( ) ( ) ( ) ( )  − (  )         +     = −  −    −     =  = − −      =   −  = −                                  dV E H d t B H t D E JdV E E H t B H t D f v E J E H t B E H H E E H H V V S E H t B H t D E t w        =    +    =    令： ,   =  =  V V E JdV f vdV dt dA        −   = − −     = −     S d dt dW dV S d t w dt dA V 则： W wdV V = 机动 目录 上页 下页 返回 结束