One fine morning, Mr. Ravi visited Gandhi park with his grandson. When he was just on a bridge over the lake in the park, an old wooden toy dropped from his hand. The toy went straight down to hit the surface of calm water, then sank into water to a certain depth below water surface and returned back due to upthrust of water to the hands of Mr. Ravi in the same position from where it was dropped. Assuming this position to be at height $$19.6\,\text{m}$$ above the surface of water, and density of material of toy to be just half the density of water in lake, the total time in which toy is received back to the hand of Mr.Ravi is calculated to be