Compute the response of a spring-mass system modeled by equation (2.2) to a force of magnitude 23 N, driving frequency of twice the natural frequency, and initial conditions given by x0 = 0 m and v0 = 0.2 m/s. The mass of the system is 10 kg, the spring stiffness is 1000 N/m, and the mass of the spring is considered and known to be 1 kg. What percent does the natural frequency change if the mass of the spring is not taken into consideration?