試題詳解

9. (5%) An undamped string/mass system, in which the mass m = 1 slug and the spring constant k = 10 lb/t, is driven by the 2-periodic external force F(t) = 1-t,0 ＜t＜2； f(t+2) = f(t). Assume that when f(t) is extended to the negative t-axis in a periodic manner, the resulting function is odd. Find a particular solution Xp(t).

(A) p(t)=nπt,
(B)s=nπ,
(C) k=nπ,
(D) k=n²n²,
(E) s=n²n²,