1. The problem statement, all variables and given/known data Hello. I have this problem: I have a ring which is sliding along a wire in the shape of a spiral because of gravity. Spiral (helix) is given as the intersection of two surfaces: x = a*cos(kz), y = a*sin(kz). The gravity field has the z axis direction. I have to find motion equations and find the wire reaction as a function of time. 2. Relevant equations I have to solve it with this equation: 3. The attempt at a solution This is the first time, when I solve a example with Lagrangian equations, so I am not sure what to do. I created this equations: I know, it is not the end. I have to find λ, motion equations and the wire reaction. But firstly, please, tell me, if I am right or where is mistake and why. Then I will continue. Thank you very much.