As television cable is pulled from a large spool to be strung from the telephone poles along

Question:

As television cable is pulled from a large spool to be strung from the telephone poles along a street, it unwinds from the spool in layers of constant radius (see accompanying figure). If the truck pulling the cable moves at a steady 6 ft / sec (a touch over 4 mph), use the equation s = rθ to find how fast (radians per second) the spool is turning when the layer of radius 1.2 ft is being unwound.