The triangle shown in Figure 1-2 is a convenient memory device for

the force-area-pressure formulas.

It helps you recall the three

factors involved: F, A, and P.

Because the F is above the line in

the triangle, it also reminds you that in both formulas indicating

division, F is always divided by one of the other two factors.

Figure 1-2.

Relationship of Force, Area, and Pressure.

TRANSMISSION OF FORCE

Two means of transmitting force are through solids and through

liquids.

Since this text is on hydraulics, the emphasis is on

fluids.

Force transmission through solids is presented only as a

means of comparison.

Transmission of Force Through Solids. Force applied at one point

on a solid body follows a straight line undiminished to an opposite

point on the body. This is illustrated in Figure 1-3.

Transmission of Force Through Confined Liquids.

Applied forces

are transmitted through bodies of confined liquids in the manner

described by Pascal's Law.

This law of physics, formulated in the

seventeenth century by the French mathematician Blaise Pascal,

states: pressure applied to any part of a confined liquid is

transmitted without change in intensity to all parts of the liquid.

This means that wherever it is applied on the body of liquid, pressure

pushes equal force against every square inch of the interior surfaces

of the

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