Page 20 - ebook fluid mechanics_finalize

FLUID MECHANICS

2 (TWO) important principles about pressure;

• Pressure acts uniformly in all directions on a small volume of fluid.

• In a fluid confined by solid boundaries, pressure acts perpendicular to

the boundary. These principles, called Pascal’s Law

1.3.1 Relationship Between Pressure and Depth

In this section, we are going to look into the relationship between pressure and

depth. Pressure, (P) at any point in the fluid can be written in terms of a column

high pressure fluid space that is, h which will result in the occurrence of such

pressure.

Figure 1.6: Relationship between pressure and depth

1.3.2 Basic Equation based on Relationship Between Pressure and Depth

Consider a vessel containing some liquid as shown in Figure 1.6 & 1.7 We know that

the liquid will exert pressure on all sides and the bottom of the vessel. Let a cylinder

be made to stand in the liquid as shown in the figure. The weight of liquid contained
in the cylinder is ωhA where ;

ω = Specific weight of the liquid

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( where is water = 1000 kg/m x 9.81 m/s )

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