Continuation of Problem 8 and Problem 37. Another explanation for the sliding stones of Racetrack Playa in Death Valley, California is that the stones move only when the water dumped on the playa during a storm freezes into a large, thin sheet of ice. The stones are trapped in place in the ice. Then, as air flows across the ice during a wind, the air-drag forces on the ice and stones move them both, with the stones gouging out the trails. The magnitude of the air-drag force on this horizontal "ice sail" is given by Dice = 4Cice?Aicev2, where Cice is the drag coefficient (2.0 × 10-3), ? is the air density (1.21 kg/m3), Aice is the horizontal area of the ice, and v is the wind speed along the ice. Assume the following: The ice sheet measures 320 m by 690 m by 4.9 mm and has a coefficient of kinetic friction of 0.11 with the ground and a density of 917 kg/m3. Also assume that 100 stones of mass 24 kg are trapped in the ice. To maintain the motion of the sheet, what is the required wind speed near the sheet?