3.90 Two men, a tall one and a short one, travel up identical inclines, pulling identical spools by means of ropes wrapped around the hubs. (See Figure P3.90.) The men travel at the same constant speed, and the ropes are wrapped in the opposite directions indicated. If the spools do not slip on the plane, one of the men will be run over by his own spool. Prove which one it is, and show how long it will take, from the instant depicted, for the spool to roll over him. 17 cm Figure P3.98 R-4 cm