A pendulum 3 m long and having a mass of 20 kg is dropped when the cable supporting it makes an angle of 45 degrees from the vertical. A 4 kg block of wood is placed at the balance point of the pendulum. Suppose that at the moment of collision with the block, the pendulum bounces to a height of 58 cm, and the block is set in motion on a rough horizontal surface. Determine the force of friction, if the latter stops in 2 s.

Hint: the answer should be 10.8 N