1. The problem statement, all variables and given/known data A rod is placed between two smooth perpendicular walls such that each end of the rod touches a wall. The rod is released with the bottom end making an angle @ with the horizontal (ground). Using the concept of instantaneous axis of rotation find the following: (a) The initial angular acceleration (b) the path of the centre of mass (c) The instantaneous acceleration of the center of mass 2. Relevant equations 3. The attempt at a solution I attempted the question first without instantaneous axis of rotation and managed to solve it using Newton's Laws, torque equations and constraint relations (although i could not do the last part) But this instantaneous axis of rotation I have never heard about. Can you please explain it to me what it is and its use here or in some simpler cases so that i can get the hang of it?