DISCUSSION THREAD

Here you will use the moving reference frame kinematics equations:
          v_P = v_O + (v_P/O)_rel + ω x r_P/O
          a_P = a_O + (a_P/O)_rel + α x r_P/O + 2ω x (v_P/O)_rel + ω x (ω x r_P/O)

With the observer attached to arm OAB:

• The angular velocity of the observer is angular velocity of the arm:
            ω = ω_OA k
• The angular acceleration is the time derivative of the angular velocity vector: α = dω /dt.
• For the (v_P/O)_rel and (a_P/O)_rel  terms, you need to ask the question: What is the velocity and the acceleration of point P as seen by the observer?
• Note also that you have at your disposal the velocity and acceleration of P through the rigid body kinematics equations of arm PC.