I wanted to know how the ,mathematical concept of Torque comes(Like force comes from Newton's law). So i went and read university physics and feynman's lecture. and here is a problem I had. I am uploading a picture of Feynman's lecture, and stating my problem below about that part. But since in that pichttps://m.ak.fbcdn.net/photos-d.ak/hphotos-ak-xpf1/v/t1.0-0/s320x320/11836687_950467178349947_4485007967532677838_n.jpg?efg=eyJpIjoiYiJ9&oh=9cac19cabafcc34ce269c7978e08e302&oe=567BD963&__gda__=1447136990_bc04b8adf657c188d5e94fb7a0038b88 [Broken] we are talking about rigid body, if a force is applied in (x,y) point and that point mass goes a displacement of del x and del y, all other point masses in that rigid body also goes by a displacement as a result of this force. then when we calculate the work, it isn't sufficient to write w=Fx.delx + Fy.dely. because all points of that rigid body moves as a result of this force.