Annex A2: Basic Topics on Laws of Motion
and Evaporation
Abstract
Annex A2 showed topics on laws of movement and evaporation physics intended to
guide the reader on embedding in matters presented in the book. Momentum and
mass conservation under discrete and infinitesimal approaches, Bernoulli equation
and fluid pressure and velocity, buoyancy, boundary layer flows with stagnation
points and wake drag around circle sections, streamlined or bluff bodies include the
issues discussed. Further analysis is performed on dynamics of evaporation
involving concepts such as dry, wet or dew point temperatures, relative and
absolute humidity, or interpretation of psychometric charts.
A2.1 Newton’s Laws
An elementary approach to the physical principles of Newtonian mechanics, valid
both for the movement of bodies and of fluid particles, is useful for understanding
common phenomena in environmental physics, such as the atmospheric processes
inherent to the vertical flows of mass and energy in the atmospheric boundary layer.
The principles of classical mechanics, based on Newton’s three laws, are quite
acceptable for the normal ranges of velocity and distance despite the most recent
and correct approach to Einstein’s theory of relativity.
Newton’s First Law of motion is as follows: the whole body remains in a state of
rest or uniform rectilinear motion unless it is compelled to change that state by
external forces applied to it. The tendency of a body to maintain its state of rest or
uniform rectilinear movement translates the principle of inertia, so Newton’s First
Law is called the Law of Inertia.
Newton’s First Law is only valid in the so-called inertial reference points. In
practical terms, fixed Earth references are considered as inertial references. Strictly
speaking, the Earth’s rotational and translational movements have small
accelerations (3,4*10
−2 ms
−2 and 0,6*10
−2 ms
−2 , respectively) whose effect is
negligible in short duration movements, and hence Earth can be considered a
reference of inertia. Any inertial reference that moves at a constant speed relative to
an inertial reference (e.g. a car or an airplane) is also considered as an inertial
The Editor(s) (if applicable) and The Author(s), under exclusive license
to Springer Nature Switzerland AG 2021
A. Rodrigues et al., Fundamental Principles of Environmental Physics,
https://doi.org/10.1007/978-3-030-69025-0
333
and Evaporation
Abstract
Annex A2 showed topics on laws of movement and evaporation physics intended to
guide the reader on embedding in matters presented in the book. Momentum and
mass conservation under discrete and infinitesimal approaches, Bernoulli equation
and fluid pressure and velocity, buoyancy, boundary layer flows with stagnation
points and wake drag around circle sections, streamlined or bluff bodies include the
issues discussed. Further analysis is performed on dynamics of evaporation
involving concepts such as dry, wet or dew point temperatures, relative and
absolute humidity, or interpretation of psychometric charts.
A2.1 Newton’s Laws
An elementary approach to the physical principles of Newtonian mechanics, valid
both for the movement of bodies and of fluid particles, is useful for understanding
common phenomena in environmental physics, such as the atmospheric processes
inherent to the vertical flows of mass and energy in the atmospheric boundary layer.
The principles of classical mechanics, based on Newton’s three laws, are quite
acceptable for the normal ranges of velocity and distance despite the most recent
and correct approach to Einstein’s theory of relativity.
Newton’s First Law of motion is as follows: the whole body remains in a state of
rest or uniform rectilinear motion unless it is compelled to change that state by
external forces applied to it. The tendency of a body to maintain its state of rest or
uniform rectilinear movement translates the principle of inertia, so Newton’s First
Law is called the Law of Inertia.
Newton’s First Law is only valid in the so-called inertial reference points. In
practical terms, fixed Earth references are considered as inertial references. Strictly
speaking, the Earth’s rotational and translational movements have small
accelerations (3,4*10
−2 ms
−2 and 0,6*10
−2 ms
−2 , respectively) whose effect is
negligible in short duration movements, and hence Earth can be considered a
reference of inertia. Any inertial reference that moves at a constant speed relative to
an inertial reference (e.g. a car or an airplane) is also considered as an inertial
The Editor(s) (if applicable) and The Author(s), under exclusive license
to Springer Nature Switzerland AG 2021
A. Rodrigues et al., Fundamental Principles of Environmental Physics,
https://doi.org/10.1007/978-3-030-69025-0
333