The amplitude of the resulting free vibrations in a single degree of freedom system

Question

A single degree of freedom system having mass 1 kg and stiffness 10 kN/m initially at rest is subjected to an impulse force of magnitude 5 kN for 10^–4 seconds. The amplitude in 5 mm of the resulting free vibration is                                                                                                                

(a) 0.5                             (b) 1.0                          (c) 5.0                             (d) 10.0