1. Restore equilibrium
A wooden plank of length 1m and uniform cross-section is hinged at one end to the bottom of a tank as shown in figure. The tank is filled with water up to a height 0.5m. The specific gravity of the plank (or ratio of plank density to water density) is 0.5 . Find the angle θ that the plank makes with the vertical in the equilibrium position (exclude the case θ=0∘ )
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