(1).若拉M:
a=F/(M+m)
T=ma=Fm/(M+m) 若拉m;分子上的m改为M
(2).a=(F-u(M+m)g)/(M+m)=F/(M+m) -ug
若拉M:T=ma+umg=Fm/(M+m) ; 若拉m:同上