The shelf is designed so that it can be placed at any height on the vertical beam. The she...

The shelf is designed so that it can be placed at any height on the vertical beam. The shelf is supported by friction between the two horizontal cylinders and the vertical beam. The combined weight of the shelf and camera is W. If the coefficient of static friction between the vertical beam and the horizontal cylinders is μs, what is the minimum distance b necessary for the shelf to stay in place?