試題詳解

14.A body of mass 5.0 kg is suspended by a spring which stretches 10 cm when the mass is att displaced downward an additional 5.0 cm and released. Note that the accele g = 9.8 m/s². Its position as a function of time is approximately
(A)-0.10 sin 9.9t m 
(B)-0.10 cos 4.9t m
(C) -0.05 cos 4.9t m
(D) -0.05 sin 4.9t m
(E) -0.05 cos 9.9t m.