1. The problem statement, all variables and given/known data 2. Relevant equations Euler-Lagrange equations of motion 3. The attempt at a solution Part a): Particle must move on surface (one constraint). Number of generalised coordinates = 3N - K where N = number of particles and K = constraints. Therefore 2 generalised coordinates are needed. Part b): Is the Lagrangian obtained using the symmetric axis of the cone as the vertical plane for the longitude phi? Part c): L independent of t -> Hamiltonian is constant (Total energy conserved) : L independent of phi -> Angular momentum is conserved Part d) and e) are troublesome, any help is appreciated.