How bout some switch draining oscillations.

A cylindrical tank of horizontal section ares $S=25cm^{2}$ has a hole in its bottom. The hole is closed by a thin metal plate A of area $S_{A}=5cm^{2}$ connected with a thin rod of length $l=10cm$ to a cylindrical float B of horizantal cross section area $S_{B}=10cm^{2}$ The plate rod float assembly works as a special valve . This plate rod float assembly works as a special valve. Now a tap is opened and water starts entering at a constant rate $r=10\frac{cc}{s}$ When the water level in the container reaches a particular height, The assembly lifts opening the hole through which water drains out at a rate $\eta=1.5r$ This operation operates periodically denoting mass of the assembly by $m=100g$ and density of water by $\rho_{o}=1g/cm^{3}$ .Find the time interval $\tau$ in minutes between closing and subsequent opening of the hole. Neglect the force created by water flow and the atmospheric pressure.