A particle of mass 'm' is rigidly attached at 'A' to a ring of mass '3m' and radius 'r' as shown. The system is released from rest and rolls without sliding. The angular acceleration of ring just after release is:

I am getting different angular accelerations of the ring using point P (Instantaneous Axis of Rotation) and Centre of Mass. When solving about point P the only torque acting is mgr by the particle. When solving about centre of mass torque by friction and particle is acting on the system.

I am aware that this seems like a 'do my homework question' but I do not want anyone to solve the question for me. I just want to know if there is something wrong about my understanding of Rolling motion.

  • $\begingroup$ I'm not sure what the two answers you're getting are, but, if in doubt, you should consider it as a free body system, with gravity (known), the surface normal (opposite of gravity) and friction acting on it. Rolling motion occurs when angular and lateral acceleration are balanced (so that the point of contact doesn't slide). $\endgroup$
    – Alex K
    Jan 7, 2023 at 0:43
  • $\begingroup$ Welcome James to Physics Stack Exchange. What is "IAOR"? (Acronyms should always be defined or linked, even if you think everyone knows.) Identifying the Centre of Mass as point O (or is it not?) would also speed up reader comprehension of your question and make it clear that you know this. You may want to look at the answer to Does angular momentum depend on the origin?. $\endgroup$ Jan 7, 2023 at 16:27