Elasticity and Fluid Physics

Karl Andre O. Ortiz

Chapter objectives

• Familiar with the different properties of matter• Differentiate between stress and strain• Learn how man harnessed the concept of

pressure to invent and develop useful applications

• Distinguish hydrostatics from aerodynamics• Show how airplanes fly using the concept of

aerodynamics

Matter

-it is the substance of which all objects are made-it also can be changed into energy and energy

into matter-has mass and occupies space

-has many forms

Structure of MatterMatter is composed of tiny particles called molecules

and in these structures, ATOMS linked together consist it.

ATOMS are made up of particles called protons, neutrons, and electrons.Protons- positively chargedNeutrons- electrically neutralElectrons- negatively charged

These particles are composed of point-like units called QUARKS. Particles smaller than atoms are called sub atomic particles

Differences between electric charge holds the atom together

electrons whirl around the nucleusin lavers called electron shells

the outermost shells are not tightly bound to the nucleus,as a result some outermost electrons can be shared. Theseelectrons are called IONS

MATTER has many forms

3 basic states:1. Solid 2. Liquid3. Gas

Other states of matter

• Plasmas• Superfluids• Superconductors• Bose-Einstein Condensates• Antimatter or Darkmatter

Chapter objectives

Familiar with the different properties of matter• Differentiate between stress and strain• Learn how man harnessed the concept of

pressure to invent and develop useful applications

• Distinguish hydrostatics from aerodynamics• Show how airplanes fly using the concept of

aerodynamics

Density and Specific Gravity

Density is the mass or the specific amount of matter in an object.

D = M/V Where: M is massV is volume

Density in Solids• Regularly shaped• Irregularly shaped

Density in GasesIs difficult to measureMass – First weigh an empty container. Next, fill the

container with the gas and weigh it again. Then subtract the first measurement to the second

Volume – measure the amount of water that the container can hold

Stress and StrainTensile stress – the ratio of the applied force F to the cross-

sectional area AStress = Force/Area = F/A

Tensile strain – defined as the ratio of the change in length ΔL to the initial length Lₒ before the force was applied. This strain refers to the change in length

Strain = change in length/initial length = ΔL/Lₒ

Young’s Modulus of Elasticity – the amount of strain an object undergoes depends on the amount of stress applied to it.

Y = stress/strain = (F/A)/(ΔL/Lₒ)

The ratio of stress to the corresponding strain

Elastic Limit - refers to the maximum stress that can be applied to an object without its breaking up, or being permanently deformed

Chapter objectives

Familiar with the different properties of matterDifferentiate between stress and strain

• Learn how man harnessed the concept of pressure to invent and develop useful applications

• Distinguish hydrostatics from aerodynamics• Show how airplanes fly using the concept of

aerodynamics

Fluid Statics

When a fluid is at rest the forces exerted are those due to the static conditions

• Hydrostatics• Pressure• Buoyancy

Pressure in Fluids

Pressure is a force exerted over an area and is measured in Pascals (Pa)

P (in Pa) = Force (in newtons) Area (in m²)

Absolute pressure = gauge pressure + atmospheric pressure

Three properties of pressure in a Fluid

1. The forces of fluids at rest exert on the walls of its container, and vice versa, and always act perpendicular to the walls.

2. An external pressure exerted on a fluid is transmitted uniformly throughout the volume of the liquid (Pascal’s Principle)

3. The pressure on small surface in a fluid is the same regardless of the orientation of the surface