The forced oscillations of a body of mass m on a spring of modulus k (as shown in Figure 2) are governed by the ODE:
my'' + cy' + ky = r(t)
where y(t) is the displacement from rest, c is the damping constant, k is the spring constant (spring modulus), and r(t) is the external force depending on time, t.
a) Let m = 1 g, c = 0.05 g/s, and k = 25 g/s^2. Write the ODE of the system.
b) Given the external force r(t) (measured in g cm/s^2), plot the external force r(t). Then, determine the Fourier Series of r.
c) Based on parts a and b, find the steady-state solution y(t) = Acos(nt) + Bsin(nt) by showing that:
4(25 - n^2)n = 0.2
d) Plot the steady-state solution y(t).