1. The problem statement, all variables and given/known data A metal ring of mass m and radius R is placed on a smooth horizontal table and is set rotating about its own axis with a constant angular speed ω. What is the tension in the ring ? 2. Relevant equations 3. The attempt at a solution Consider a small element ds=rdθ .Tension T acts at the two ends .If I resolve tension in horizontal and vertical components Tcosdθ/2 and Tsindθ/2 respectively , the horizontal components cancel and the vertical components add up . The net vertical component F = 2Tsindθ/2 . Now here I am little unsure how this F is acting as the component of force providing the required centripetal acceleration to this element ds .It is the direction of this force which is troubling me. How is F acting along the line joining the mid-point of this small segment ds to the center of the ring (radial direction)? My thinking is that it is because the Center of Mass of the element ds lies somewhere along this line joining the mid point of ds to the center of the ring . Should I consider F to act at the mid point of the element ds OR to act at the COM of the element OR something else ? Could somebody help me understand this . Many thanks .