A wooden cylinder of diameter ‘4r’, height ‘h’ and density ‘ $\rho /3$’ is kept on a hole of diameter ‘2r’ of tank, filled with liquid of density ‘$\rho$ ’ as shown in the figure.

Now level of the liquid starts decreasing slowly. When the level of liquid is at a height 
‘$h_1$ ’ above the cylinder the blocks starts moving up. At what value of ‘$h_1$ ’ will the block rise is $\frac{nh}{3}$ , n will be