Dynamics 2. Work done by a variable force: 2 Elementary work ]w=Fcosads =Fd=F·cr Xdx+ydy+zd Myar (F=Xi +yj+Zk, dr=dxi +dv+dck Fdr= Xdx+Yay+ld)x The total work done by a force F during a finite curvilinear displacement M, M2is W=∫ Fcosads=∫Fds M (expression in the natural form) =∫Fb (vector expression) M =「Xax+1hy+z (expression in terms of rectangula lar coordinates) 77 2. Work done by a variable force: W =Fcosds F ds =  = F dr = Xdx +Ydy + Zdz (F = Xi +Yj + Zk ,dr = dxi + dyj + dzk F dr = Xdx+Ydy + Zdz) Elementary work The total work done by a force during a finite curvilinear displacement is . F M1 M2 =  =  2 1 2 1 cos M M M M W F ds F ds   (expression in the natural form)  =  2 1 M M F dr (vector expression)  = + + 2 1 M M Xdx Ydy Zdz (expression in terms of rectangular coordinates)