The sled slides along on a thin horizontal layer of water between the ice and the runners. The horizontal force that the water puts on the runners is equal to 1.2lb when the sled's speed is 50ft/s. The total area of both runners in contact with the water is 0.08ft² , and the viscosity of the water is 3.5 x10^-5 lb s/ft². Determine the thickness of the water layer under the runners. Assume a linear velocity distribution in the water layer.