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 Matter
Matter 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 charged
Neutrons- electrically neutral
Electrons- 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 nucleus
in lavers called electron shells
the outermost shells are not
tightly bound to the nucleus,
as a result some outermost
electrons can be shared. These
electrons are called IONS
MATTER has many forms
3 basic states:
1. Solid
2. Liquid
3. 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 mass
V is volume
Density in Solids
• Regularly shaped
• Irregularly shaped
Density in Gases
Is difficult to measure
Mass – 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 Strain
Tensile stress – the ratio of the applied force F to the crosssectional area A
Stress = 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
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
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