1. The problem statement, all variables and given/known data A wedge of mass M and angle [alpha] slides freely on a horizontal plane. A particle of mass m moves freely on the wedge. Determine the motion of the particle as well as that of the wedge. Note: We are supposed to use the Lagrangian formulation of mechanics to solve this problem. 3. The attempt at a solution Okay, here's what I've got so far: We can write the position of the mass m as x = l cos [alpha]; y = l sin [alpha] where l is the length of the hypotenuse of the wedge that the mass is sliding on. Thus, the kintetic energy of the mass m is equal to [(1/2)m][l^2 cos^2(alpha) - l^2 sin^2(alpha)]; the potential energy is equal to [l sin(alpha)][mg]. Therefore, the Lagrangian can be written as L = [(1/2)l^2m(cos^2(alpha) - sin^2(alpha))] - [l sin(alpha)][mg]. And that's as far as I've gotten; I'm having trouble with the rest. Help is appreciated greatly.