Let the position of the mass center, G, be measured by a coordinate x that is parallel to the inclined plane and positive down the plane, with origin where the spring is undeterred. Obtain the equation of motion (ODE) that governs the system\'s motion. Solution Resultant spring constant = 2k * k /(2k+k) = 2k/3 Resultant C = 2C/3 Differential force equation is -2k/3 x + 2C/3 x\' + mg = mx\".