Daniel Bernoulli (1700-1782)

• Swiss scientist with a “bad dad” (who was head of mathematics at nearby Groningen University in the Netherlands)

“Hydrodynamica, by Daniel Bernoulli, Son of Johann”

His dad tried to take credit for the book, renaming it “Hydraulica”, he later banned Daniel from his house

Bernoulli’s Principle• States that as the velocity of a fluid is

increased, the pressure exerted by that fluid is decreased.

Atomizers/Paint sprayers

Forces Within Fluids

• Surface Tension—Result of the cohesive (similar materials attracting) forces among the particles of a liquid, stronger at surface, forms a sort of “film”

• Capillary action—result of adhesion (dissimilar materials attracting) between water molecules and molecules of another material such as glass, or a paper towel.

Intermolecular forces not equally distributed on particle at surface

Overall, net downward force on particles at surface causes them to be slightly compressed, and act like a tightly stretched rubber sheet.

Concave Meniscus, as with water and glass

Convex meniscus, as with mercury and glass

Capillary Action—what is the relationship between diameter of tube and height of fluid?

13.2 The Solid State

• There are three basic types of solids– Crystalline—having a structure where the

atoms, ions, or molecules are arranged in regular, 3-dimensional patterns

– Amorphous—having no particular structure– Composite—engineered solids made up of 2

or more solids with distinctly different properties

Crystalline solids

• The fixed pattern of arrangement is called the “Crystal Lattice”

Examples of three types of crystalline solids. Only part of the structure is shown in each case.

Amorphous solids

Composites• Composite materials are said to have two

phases.

• The reinforcing phase is the fibers, sheets, or particles that are embedded in the matrix phase.

• The reinforcing material and the matrix material can be metal, ceramic, or polymer.

• Typically, reinforcing materials are strong with low densities while the matrix is usually a ductile, or tough, material

Composites

• Some of the common classifications of composites are: – Reinforced plastics – Metal-matrix composites – Ceramic-matrix composites – Sandwich structures – Concrete

CompositesSpaceship One

Concrete

Carbon fiber

Engineered I-beams, laminated

Oriented-Strand Board (OSB)

Elasticity in Solids

• Elasticity is the ability of a material to return to its original form when external forces are removed.

• If too much deformation occurs, the material may surpass its “elastic limit” and be permanently deformed.

Effects of Temperature Change on Solids

• As most solids cool, the particles get closer together, the solid contracts

• As most solids are heated, the particles get farther apart, the solid expands

• Water is the unusual solid…..as it begins to freeze, it actually will expand in volume, and as a result, will become less dense.

Bimetallic strip: made up of two different metals bonded to each other. Strip bends when heated because each metal will expand at its own rate. The strip bends away from the metal with the greatest expansion rate.

Volume Expansion