4.12 A cylindrical tank, of diameter D=50 mm, drains through an opening, d =5 mm., in the bottom of the tank. The speed of the liquid leaving the tank is approximately V = 2gy where y is the height from the tank bottom to the free surface. If the tank is initially filled with water to y0 =0 4 m, determine the water depths at t =60 sec, t =120 sec, and t =180 sec. Plot y (m) versus t for the first 180 sec.