This NASA video segment explores how Newton's Laws of Motion apply to the lift of an airplane. An instructor at NASA's National Test Pilot School teaches that for an airplane to overcome the downward force of its weight, it must change the momentum of the air molecules colliding with the wings. This is accomplished by changing the air's vertical velocity through increased propeller speed, sharpened angles of attack, widened wings or curved wings. Onscreen formulas and calculations represent the forces mathematically. For example, in one part, the instructor derives a formula from Newton's second law to calculate the minimum flying speed of an aircraft. The instructor then flies the aircraft to test his calculations.