1. The problem statement, all variables and given/known data Hi all. I've got a vertical rod on a surface with a fixed and frictionless pivot at bottom end. The rod of length L is released and begins to fall. The forces acting on the CM of the rod should be: - weight force: mg - centripetal (radial) force: m*L/2*omega^2 - tangential force: m*L/2*alfa 2. Relevant equations 3. The attempt at a solution I tryied to calculate the vertical and horizontal resulting force but without success. Assuming the positive sign in the sense of forces increasing teta angle, the balance of vertical components I think should be: N = m*L/2*alfa*sin(teta) + mg + m*L/2*omega^2*cos(teta) Expressing alfa and omega in terms of weigth force (respectively from tau = I*alfa and PE = 1/2*I*omega^2) I've got: N = 3/4mg*sin^2(teta) + mg + 3/2mg*cos(teta) Where first and third terms of right member are the vertical component of tangential and centripetal forces. This result is clearly not correct because at 90° the normal force should be zero. Could anybody check this result ? Thank you.