A spring-mass system consists of a mass weighing \(100 \mathrm{~N}\) and a spring with a stiffness of \(2000 \mathrm{~N} / \mathrm{m}\). The mass is subjected to resonance by a harmonic force \(F(t)=25 \cos \omega t \mathrm{~N}\). Find the amplitude of the forced motion at the end of

(a) \(\frac{1}{4}\) cycle,

(b) \(2 \frac{1}{2}\) cycles, and

(c) \(5 \frac{3}{4}\) cycles.