The equation for the displacement u for an unforced mass-spring-dashpot system, with respect to its equilibrium point due to gravity, is given by du(t) c du(t) k dt2 m dt -+-u(t) = 0 + m with the spring and viscous parameters given by k and c, and the mass m. By doing u' = v convert the second-order ODE into a system of two first-order ODEs, and solve the system by writing a MATLAB code using RK4 and MATLAB command ODE45. Include: - a figure for the position u with both methods - a figure for the velocity v with both methods - a figure for the difference between both positions u Use axes labels, and legends when necessary. Consider u(0) = 0 m, u'(0) = -2 m/s, m = 25 kg, k = 200 N/m, and c = 25 Ns/m. Use a time vector given by t = [0 0.1 0.2 0.3 0.4 19.8 19.9 20 seconds