PRESSURE
Alina&Zhaniya 10"V”
What is pressure?
Pressure is defined as the force per unit area applied to
an object's surface. It is a measure of how much force
is distributed over a given area.
P=F/A
Where:
P is the pressure.
F is the force applied perpendicular to the surface.
A is the area over which the force is distributed.
Pressure is typically expressed in units such as pascals
(Pa), newtons per square meter (N/m²), or in some
cases, atmospheres (atm) or pounds per square inch
(psi), depending on the context.
Molecular structure of Solids,Liquids
and Gases
Solids have a highly ordered molecular
structure, with particles closely packed
in a fixed arrangement. These particles
vibrate but don't move freely.
Liquids have a less ordered structure
with particles that are still close
together but can move past one
another. They have more kinetic energy
than solids, allowing them to flow.
Gases have a very disordered molecular
structure with particles that are far apart
and have high kinetic energy. Gases fill the
entire volume of their container.
Pressure of solids
The pressure in solids, often referred to as mechanical
pressure, is the force per unit area applied to a solid
material. It is a measure of how the internal forces within
a solid are distributed over a given area. The pressure in
solids can be described as a result of the atomic or
molecular interactions within the material.
In solids, the pressure can vary depending on factors
like the magnitude and direction of the applied
force, the material's properties, and the area over
which the force is applied. When a solid is under
compression (being pushed or squeezed), the
pressure within the material increases. When a solid
is under tension (being pulled or stretched), the
pressure decreases.
Pressure of liquids
The pressure of a liquid, often referred to as hydrostatic
pressure, is the force per unit area exerted by a liquid on the
walls of its container or any submerged object within the
liquid. This pressure is a result of the weight of the liquid
above a certain point in the liquid column, as gravity pulls the
liquid downward.
P=ρ⋅g⋅h
Where:
P is the hydrostatic pressure.
ρ (rho) is the density of the liquid.
g is the acceleration due to gravity.
h is the depth of the liquid from the surface to the point
where you want to measure the pressure.
Pressure of gases
The pressure of a gas is the force per unit area
exerted by the gas molecules on the walls of
their container. It is the result of gas
molecules colliding with the walls of the
container and is a measure of the gas's
tendency to expand and fill the available
space.
PV=nRT
Where:
P is the pressure of the gas.
V is the volume of the gas.
n is the number of moles of the gas.
R is the ideal gas constant.
T is the absolute temperature of the gas
(measured in Kelvin).
Hydraulic
Machines
Hydraulic machines use liquid fluid power
to perform work. Heavy construction
vehicles are a common example. In this
type of machine, hydraulic fluid is pumped
to various hydraulic motors and hydraulic
cylinders throughout the machine and
becomes pressurized according to the
resistance present.
Measurement of atmospheric
pressure
Measurement of atmospheric pressure is important in
meteorology, aviation, and various industrial and scientific
applications. Barometers are commonly used instruments
to measure atmospheric pressure.
Atmospheric measurement - ments include winds,
temperature, pressure, humidity, dew point, moisture,
radiation, visibility, cloud heights, lightning, gaseous
composition (e.g., CO2, pollutants), aerosols, and
precipitation.
communicating
pressure vessels
When two containers containing the same liquid
are connected by a pipe, the liquid levels in both
containers will be at the same height, illustrating
Pascal's Principle. This principle is the basis for
hydraulic systems.
Communicating under pressure is a critical
leadership component learned very early on during
Navy SEAL training. Without having the ability to
maintain composure, thinking clearly, gather
information and make a call, you can't succeed in
combat. Which of course can lead to the worst
possible outcome.