Uson sprint iq, Руководство пользователя

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Reference
87
5.0.6 Concepts Applicable to Testing
Pressure
In physics, pressure is a force measured in terms of its
distribution over an area of an opposing force. This is
expressed as force (F) divided by unit area (A) of the surface
area to which the force is applied. Air pressure most
commonly refers to a force exerted uniformly in all directions.
Force X Area = pressure.
Absolute pressure is pressure measured with respect to zero
pressure (a very high vacuum)
Gauge pressure is pressure measured with respect to
surrounding air pressure (the pressure exerted by the weight
of the atmosphere).
Barometric pressure is the surrounding pressure caused by the
atmosphere. At average sea level, barometric pressure is about
14.7 pounds per square inch, or 29.9 inches of mercury. This
is equivalent to 101.3 Kilopascals.
Negative Pressure (Vacuum)
A vacuum can be defined as a volume of space that contains
no matter. For practical purposes, this means a volume where
as much matter as possible has been removed. A perfect
vacuum does not exist even in the depths of space. Any given
volume will probably contain one or more particles of matter
or one or more units of energy, which is the equivalent of
matter (relativity). Even a vacuum with no measurable energy
level is only a “virtual” vacuum.
Air Composition
The atmosphere is composed almost entirely of oxygen and
nitrogen in their diatomic forms (two atoms bound together
by chemical forces). Diatomic nitrogen makes up about 78%