The two blocks in the figure below are connected by a massless rope that passes over a pulley

The two blocks in the figure below are connected by a massless rope that passes over a pulley. The pulley is 15 cm in diameter and has a mass of 3.0 kg. As the pulley turns, friction at the axle exerts a torque of magnitude 0.55 N/m. If the two blocks are released from rest, how long does it take the 4 kg block to reach the floor?
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