A rectangular tank used to supply water for a Reynolds flow experiment is \(230 \mathrm{~mm}\) deep. Its width and length are \(W=150 \mathrm{~mm}\) and \(L=230 \mathrm{~mm}\). Water flows from the outlet tube (inside diameter \(D=6.35 \mathrm{~mm}\) ) at Reynolds number \(R e=2000\), when the tank is half full. The supply valve is closed. Find the rate of change of water level in the tank at this instant.