A horizontal plywood disk with mass 6.50 and diameter 1.16 pivots on frictionless bearings about a vertical axis through its center. You attach a circular model-railroad track of negligible mass and average diameter 1.06 to the disk. A 1.50 , battery-driven model train rests on the tracks. To demonstrate conservation of angular momentum, you switch on the train's engine. The train moves counterclockwise, soon attaining a constant speed of 0.700 relative to the tracks. Find the magnitude and direction of the angular velocity of the disk relative to the earth.