A jet with mass m = 90000.0 kg jet accelerates down the runway for takeoff at 1.6 m/s2.
3) 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.
5) After reaching cruising altitude, the plane levels off, keeping the horizontal speed constant, but smoothly reducing the vertical speed to zero, in 13.0 seconds.
What is the net vertical force on the airplane as it levels off?