Answer Happy

USE MATLAB!!
The elastic force on the landing gear after touchdown may exhibit a nonlinear stiffening behavior as a function of aircraft vertical displacement. In this case, the SDOF equation of motion for vertical displacement of the aircraft may be expressed as my¨​+cy˙​+Fs​(y)=mg with y defined positive downward. Fs​(y) is a nonlinear spring force. Use a numerical integration technique such as the Euler's method or the RK4 method ('ode45' in MATLAB) to determine vertical displacement of an aircraft with the following characteristics: Aircraft weight: 2,100 lb Damping constant: 200 lb-s/in. Sink velocity at touchdown: 15ft/sec Spring force: Fs​(y)=Ky(1+0.25y^​2 ), where K=725lb/ in and y^​=0 if ∣y∣ (measured in inches) is less than 3 inches; otherwise, y^​=∣y∣−3.