1. The problem statement, all variables and given/known data A cylinder on a inclined plane is rolling without slipping. Inclined plane is connected to wall with a spring and cylinder is connected to wall with a spring too. All frictions will be neglected, and all the given data has shown on the image below. As seen above, k2 spring and cylinder is only moving at vertical axis which can be thought as y. 2. The attempt at a solution First of all, i have doubts on generalized coordinates. I think only one generalized coordinate should be used and it should be y. I need to solve this problem with D'Alembert Principle and Lagrangian Dynamics. Thank you in advance for your help.