fluid force on vertical side of a trapezoid tank the weight density of water is 62.4

However, for other nonrectangular shapes, integration would generally be needed to determine the volume and centroid. The use of pressure prisms for determining the force on submerged plane areas is convenient if the area is rectangular so the volume and centroid can be easily determined. The resultant fluid force acting on a submerged area is affected by the pressure at the free surface. ■ FIGURE 2.21 Pressure variation along an inclined plane area. Although it is usually convenient to measure distances along the inclined surface, the pressures developed depend on the vertical distances as illustrated. In this instanceĪnd y: and y2 can be determined by inspection.įor inclined plane surfaces the pressure prism can still be developed, and the cross section of the prism will generally be trapezoidal as is shown in Fig. The location of FR can be determined by summing moments about some convenient axis, such as one passing through A. Where the components can readily be determined by inspection for rectangular surfaces. Specific values can be obtained by decomposing the pressure prism into two parts, ABDE and BCD, as shown in Fig.

However, the resultant force is still equal in magnitude to the volume of the pressure prism, and it passes through the centroid of the volume. In this instance, the cross section of the pressure prism is trapezoidal. This same graphical approach can be used for plane surfaces that do not extend up to the fluid surface as illustrated in Fig. This result can readily be shown to be consistent with that obtained from Eqs. For the volume under consideration the centroid is located along the vertical axis of symmetry of the surface, and at a distance of h/3 above the base (since the centroid of a triangle is located at h/3 above its base).

The resultant force must pass through the centroid of the pressure prism. The magnitude of the resultant fluid force is equal to the volume of the pressure prism and passes through its centroid. Graphical representation of hydrostatic forces on a vertical rectangular surface.

Pressure prism for vertical rectangular area. Where bh is the area of the rectangular surface, A.

Fluid force on vertical side of a trapezoid tank the weight density of water is 62.4