Dynamics (physics)

Structuring the mechanics from the point of view of the forces involved
mechanics                                             Kinematics Laws of motion without forces   Dynamics effect of forces                                             Statics Forces in equilibrium of resting bodies   Kinetic forces change the state of motion

The dynamics of ( ancient Greek dynamis , power ') is the branch of mechanics that deals with the effects of forces involved. In physics , dynamics is understood to mean the description of the movement of bodies in their dependence on the forces acting on them.

In the more general sense, dynamics in physics describes the (temporal) behavior of a dynamic system and the equations of motion on which it is based.

There are different classifications of the dynamics.

physics

In physics, dynamics are divided into statics , which deal with the case of the equilibrium of forces (unaccelerated bodies) and kinetics , which deal with accelerated bodies. In contrast to this, kinematics, as a further area of ​​mechanics, is limited to a geometric description of the movements without taking forces into account.

Technical mechanics

The dynamics in technical mechanics
Technical mechanics                                                           Statics   dynamics   Strength theory                                             kinematics   kinetics

In technical mechanics , dynamics is understood as the theory of the movements of solid bodies. Fluid dynamics , on the other hand, deals with gases and liquids . In technical mechanics, dynamics are usually divided into

• the kinematics , which does not take any forces into account, but only describes the paths of the moving bodies geometrically and
• the kinetics , which also take forces into account.

In addition to statics and strength theory, dynamics is one of the three main areas of technical mechanics. Some also believe that dynamics consists of the two areas of statics and kinetics, but the corresponding works are divided into three volumes or chapters by all authors, one of which deals with statics and strength theory and another Kinetics and kinematics. Some of these volumes are called dynamics , others also called kinetics and kinematics or just kinetics . The contents include the kinematics and kinetics of individual point masses, of several point masses and of rigid bodies as well as vibrations . If the inertial forces are included in problems , they can be solved with methods of statics. In this respect, dynamics is methodically based on statics and is therefore only taught after statics.

The dynamics knows the following sub-areas of broader meaning:

• Machine dynamics
• Structural dynamics
• Vehicle dynamics
• Rotor dynamics

Concept history

The name “dynamics” for the theory of forces was introduced in 1695 by Gottfried Wilhelm Leibniz in his Specimen Dynamicum . Based on the teaching of Aristotle , Leibniz understood “force” to be the “material property” inherent in the respective body that moves it. He essentially identified this with what is now known as the kinetic energy of the body. In classical mechanics , which goes back to Isaac Newton , matter is absolutely passive, and the action of an external force changes its state of motion, as defined in Newton's second law of 1687 and explicitly specified by Leonhard Euler in 1739 in today's formula . ${\displaystyle F=ma}$

Web links

Wikibooks: Dynamics  - Learning and Teaching Materials

Individual evidence

1. ↑ Horst Herr: Technical mechanics - statics, dynamics, strength theory. 2008, foreword, pp. 2–4.
2. ↑ Ulrich Gabbert , Ingo Raecke: Technical mechanics for industrial engineers. Hanser, 4th edition, 2008, p. 213.
3. ↑ Mahir Sayir, Stephan Kaufmann: Engineering Mechanics 3 - dynamics. Springer 2nd edition, 2015, p. 9.
4. ↑ Jürgen Dankert and Helga Dankert: Technical Mechanics. Springer, 7th edition, 2013, p. 457.
5. ^ Gross, Hauger, Schröder, Wall: Technical Mechanics 3 - Kinetics. Springer, 13th edition, 2015, p. 1.
6. ↑ Mahnken: Textbook of Technical Mechanics - Dynamics. Springer, 2nd edition, 2012, p. 3.
7. ↑ Dreyer et al.: Technical Mechanics - Kinematics and Kinetics.
8. ↑ Gross et al.: Technical Mechanics 3 - Kinetics.
9. ↑ Mahnken: Textbook of Technical Mechanics - Dynamics. Springer, 2nd edition, 2012, foreword.
10. ↑ Mahir Sayir, Stephan Kaufmann: Engineering Mechanics 3 - dynamics. Springer, 2nd edition, 2015, foreword and p. 27.
11. ^ Max Jammer : Concepts of Force: A Study in the Foundations of Dynamics. Harvard UP, Cambridge (Mass.) 1957; Harper, New York 1962; Dover, New York 1999. ISBN 0-486-40689-X .