1. The problem statement, all variables and given/known data To derive the equations of motion for a compound pendulum. Pendulum parameters are: mass M, mass moment of inertia= Ixx,Iyy,Izz,Ixy,Iyz,Izx, Euler angles theta, phi & psi and their time-derivatives theta_dot, phi_dot, & psi_dot, and coordinates of center-of-mass (x,y,z) The coordinate system is give as; X & Y axis in horizontal plane, while Z axis point downwards. (SEE FIGURE attached with this post) https://www.physicsforums.com/attachment.php?attachmentid=27054&stc=1&d=1279608886 2. Relevant equations Kinetic energy, T = 0.5 [tex]\omega * I * \omega[/tex] Potential energy, V = -m*g*z Lagrangian, L = T - V 3. The attempt at a solution I have found the expression of c-o-m in terms of Euler angles: x = l*sin(theta)*cos(psi) y = l*sin(theta)*sin(psi) z = l*cos(theta) where, l is the distance between hinge point and c-o-m, and theta is inclination from Z axis, psi is angle between "l*sin(theta)" and X axis. Now, need to derive the expression for components of angular velocity in terms of Euler angles. How should I do that? Please help.