Q: A wooden block of mass 0.5 kg and density 800 kgm-3 is fastened to the free end of a vertical spring of spring constant 50 Nm-1 fixed at the bottom. If the entire system is completely immersed in water, the elongation (or compression) of the spring in equilibrium and the time-period of vertical oscillations of the block when it is slightly depressed and released.
(a) 6.78 cm, π/5 s
(b) 4.5 cm, π/2 s
(c) 2.5 cm, π/5 s
(d) 4.6 cm, π/6 s
Ans: (c)