[10 marks] (2) Gate AB in Fig. is a homogeneous mass of 180 kg, 1.2 m wide into the paper, hinged at 4, and resting on a smooth bottom at B. All fluids are at 20°C. For what water depth h will the force at point B be zero? Glycerin HG = 2 m ΘΑ b=1 m B 60° Water Hw