A mass of 20.0 kg is on a rough, horizontal table 3.0 m from the edge. It is connected by a light, smooth string, running at right angles to the edge of the table, to a 4.0 kg mass, which hangs vertically. The system starts from rest, and after 3.0 s the 20.0 kg mass reaches the edge of the table.
1. Draw a diagram showing the forces acting on the system.
2. Calculate the frictional force between the heavier mass and the table.