1. f = \(\frac{1}{2π} \sqrt{k/m}\)
2. f1 = \(\frac{1}{2 \pi} \sqrt{k / m}\)____(1)
3. When spring is cut in to half, spring constant becomes 2k. Hence frequency,

4. If this system is immersed in water, the amplitude of oscillation decrease quickly. Hence system comes to rest quickly.