A rectangular gate of 1m wide is hinged at its top edge, shown as bellow. There is water at the right hand side of gate; the water is at the same level as the hinge. On the top of the water at the right side of the gate there is a layer of oil with specific gravity ? = 0.85. On the left side of the gate, there is one metre high of mercury with ? =13.6. Find out the maximum height of the oil to maintain the gate closed. The gate itself is very light. Given Y= 2 m, H = 1 m and the angle between gate and the horizontal is 60o.