A jet with mass m = 90000.0 kg jet accelerates down the runway for takeoff at 1.6 m/s2. Once off the ground, the plane climbs upward for 20 seconds. During this time, the vertical speed increases from zero to 24.0 m/s, while the horizontal speed increases from 80.0 m/s to 98.0 m/s. What is the net vertical force on the airplane as it levels off?