DISCUSSION THREAD

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

With the observer attached to the tube AB:

• The angular velocity of the observer is the vector sum of the angular velocity of arm OA and the angular velocity of the tube AB relative to the arm:
            ω = Ω I + θ_dot  k
  where I is a fixed axis and k is a moving axis.
• The angular acceleration is the time derivative of the angular velocity vector: α = dω /dt.
• For the (v_P/A)_rel and (a_P/A)_rel  terms, you need to ask the question: What is the velocity and the acceleration of particle P as seen by the observer?