the graph below shows the distance of an airplane from an airport during a long flight. (a) how far was the airplane from the airport at 1 p.m.? at 2 p.m.? (b) how fast was the distance changing at 1 p.m.? (c) how could the distance from the plane to the airport remain unchanged from 1:45 p.m. until 2:30 p.m. without the airplane falling?