11. A student, standing on a scale in an elevator at rest, sees that his weight is 840 N. As the elevator rises, the scale reading increases to 1050 N, then returns to normal. When the elevator slows to a stop at the 10th floor, the scale reading drops to 588 N, then returns to normal. Determine the acceleration at the beginning and end of the trip. Make quantitative force diagrams. Write a net force equation for the axis along which forces are not balanced