Module 3: Hydrostatic forces on submerged bodies
  Lecture 8: Examples
 


Examples on forces on stationary submerged bodies

Example1:
See the drawing below. A tank is filled with water. At the bottom of the tank, a gate AB is hinged at A. To keep the gate in place, a vertical force, is applied at the distance of 1m from the hinge. Compute . Given g =10 m/s2. The width of the gate is 2 m.

(Fig. 8a)
Weight of water over AB will make the gate open in the clockwise direction. F acting vertically upward will keep the gate in place (rotational equilibrium). Note that the weight of the water-column of height 3 m will be acting on the gate and be uniform.
Therefore, 
And, this force will act at a distance of 0.75 m from A.
  (Moment about A)
(Fig. 8b)