A cylindrical block of wood (density $= 650 \mathrm {~kg} \mathrm {~m} ^ { - 3 }$), of base area $30 \mathrm {~cm} ^ { 2 }$ and height 54 cm, floats in a liquid of density $900 \mathrm {~kg} \mathrm {~m} ^ { - 3 }$. The block is depressed slightly and then released. The time period of the resulting oscillations of the block would be equal to that of a simple pendulum of length (nearly):\\
(1) 52 cm\\
(2) 26 cm\\
(3) 39 cm\\
(4) 65 cm