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Annotated color version of the original 1824 Carnot heat engine showing the hot body (boiler), working body (system, steam), and cold body (water), the letters labeled according to the stopping points in Carnot cycle Thermodynamics is a branch of natural science concerned with heat and its relation to energy and work . It defines macroscopic variables (such as temperature , internal energy , entropy , and pressure ) that characterize materials and radiation, and explains how they are related and by what laws they change with time.
Statics is the branch of mechanics that is concerned with the analysis of loads ( force and torque, or "moment" ) on physical systems in static equilibrium, that is, in a state where the relative positions of subsystems do not vary over time, or where components and structures are at a constant velocity. When in static equilibrium, the system is either at rest, or its center of mass moves at constant velocity. By Newton's first law , this situation implies that the net force and net torque (also known as moment of force) on every part of the system is zero. From this constraint, such quantities as stress or pressure can be derived. The net forces equaling zero is known as the first condition for equilibrium, and the net torque equaling zero is known as the second condition for equilibrium. See statically determinate .
The theory of relativity , or simply relativity , generally encompasses two theories of Albert Einstein : special relativity and general relativity . [ 1 ] (The word relativity can also be used in the context of an older theory, that of Galilean invariance .) Concepts introduced by the theories of relativity include: Measurements of various quantities are relative to the velocities of observers. In particular, space and time can dilate . Spacetime : space and time should be considered together and in relation to each other.
Quantum mechanics (QM – also known as quantum physics , or quantum theory ) is a branch of physics dealing with physical phenomena at microscopic scales, where the action is on the order of the Planck constant . Quantum mechanics departs from classical mechanics primarily at the quantum realm of atomic and subatomic length scales. Quantum mechanics provides a mathematical description of much of the dual particle-like and wave-like behavior and interactions of energy and matter . In advanced topics of quantum mechanics, some of these behaviors are macroscopic and only emerge at extreme (i.e., very low or very high) energies or temperatures . [ citation needed ] The name quantum mechanics derives from the observation that some physical quantities can change only in discrete amounts (Latin quanta ), and not in a continuous ( cf.
Plasma (from Greek πλάσμα, "anything formed" [ 1 ] ) is one of the four fundamental states of matter (the others being solid , liquid , and gas ). Heating a gas may ionize its molecules or atoms (reducing or increasing the number of electrons in them), thus turning it into a plasma, which contains charged particles: positive ions and negative electrons or ions. [ 2 ] Ionization can be induced by other means, such as strong electromagnetic field applied with a laser or microwave generator, and is accompanied by the dissociation of molecular bonds , if present. [ 3 ] The presence of a non-negligible number of charge carriers makes the plasma electrically conductive so that it responds strongly to electromagnetic fields . Plasma, therefore, has properties quite unlike those of solids , liquids , or gases and is considered a distinct state of matter .
Optics is the branch of physics which involves the behaviour and properties of light , including its interactions with matter and the construction of instruments that use or detect it. [ 1 ] Optics usually describes the behaviour of visible , ultraviolet , and infrared light. Because light is an electromagnetic wave , other forms of electromagnetic radiation such as X-rays , microwaves , and radio waves exhibit similar properties. [ 1 ] Most optical phenomena can be accounted for using the classical electromagnetic description of light.
Mechanics ( Greek Μηχανική ) is the branch of science concerned with the behavior of physical bodies when subjected to forces or displacements , and the subsequent effects of the bodies on their environment. The scientific discipline has its origins in Ancient Greece with the writings of Aristotle and Archimedes [ 1 ] [ 2 ] [ 3 ] (see History of classical mechanics and Timeline of classical mechanics ). During the early modern period , scientists such as Galileo , Kepler , and especially Newton , laid the foundation for what is now known as classical mechanics . It is a branch of classical physics that deals with the particles that are moving either with less velocity or that are at rest.
Mathematical physics refers to development of mathematical methods for application to problems in physics . The Journal of Mathematical Physics defines the field as: "the application of mathematics to problems in physics and the development of mathematical methods suitable for such applications and for the formulation of physical theories". [ 1 ] [ edit ] Scope
Kinematics is the branch of classical mechanics that describes the motion of points, bodies (objects) and systems of bodies (groups of objects) without consideration of the causes of motion. [ 1 ] [ 2 ] [ 3 ] The term is the English version of A.M. Ampère 's cinématique, [ 4 ] which he constructed from the Greek κίνημα , kinema (movement, motion), derived from κινεῖν , kinein (to move). [ 5 ] [ 6 ] The study of kinematics is often referred to as the geometry of motion. [ 7 ] (See analytical dynamics for more detail on usage). To describe motion, kinematics studies the trajectories of points, lines and other geometric objects and their differential properties such as velocity and acceleration.
Typical aerodynamic teardrop shape, assuming a viscous medium passing from left to right, the diagram shows the pressure distribution as the thickness of the black line and shows the velocity in the boundary layer as the violet triangles. The green vortex generators prompt the transition to turbulent flow and prevent back-flow also called flow separation from the high pressure region in the back. The surface in front is as smooth as possible or even employs shark like skin , as any turbulence here will reduce the energy of the airflow. The truncation on the right, known as a Kammback , also prevents back flow from the high pressure region in the back across the spoilers to the convergent part. In physics , fluid dynamics is a subdiscipline of fluid mechanics that deals with fluid flow —the natural science of fluids ( liquids and gases ) in motion.
The word Electromagnetism is a compound from two Greek terms, ἢλεκτρον, ēlektron , " amber " (as electrostatic phenomena were first described as properties of amber by the philosopher Thales ), and μαγνήτης, magnētēs , "magnet" (the magnetic stones found in antiquity in the vicinity of the Greek city of Magnesia , in Lydia , Asia Minor ). The science of electromagnetic phenomena is defined in terms of the electromagnetic force, sometimes called the Lorentz force , which includes both electricity and magnetism as elements of one phenomenon. The electromagnetic force is one of the four fundamental interactions in nature , the other three being the strong interaction , the weak interaction and gravitation . This force is described by electromagnetic fields , and has innumerable physical instances including the interaction of electrically charged particles and the interaction of uncharged magnetic force fields with electrical conductors.
Dynamics is a branch of physics (specifically classical mechanics ) concerned with the study of forces and torques and their effect on motion , as opposed to kinematics , which studies the motion of objects without reference to its causes. Generally speaking, researchers involved in dynamics study how a physical system might develop or alter over time and study the causes of those changes. In addition, Isaac Newton established the undergirding physical laws which govern dynamics in physics.
Physical cosmology , as a branch of astronomy , is the study of the largest-scale structures and dynamics of the universe and is concerned with fundamental questions about its formation and evolution. [ 1 ] For most of human history, it was a branch of metaphysics and religion . Cosmology as a science originated with the Copernican principle , which implies that celestial bodies obey identical physical laws to those on Earth, and Newtonian mechanics , which first allowed us to understand those laws. Physical cosmology, as it is now understood, began with the twentieth century development of Albert Einstein 's general theory of relativity , and better astronomical observations of extremely distant objects. These advances made it possible to speculate about the origin of the universe , and allowed scientists to establish the Big Bang Theory as the leading cosmological model.
Condensed matter physics is a branch of physics that deals with the physical properties of condensed phases of matter . [ 1 ] Condensed matter physicists seek to understand the behavior of these phases by using well-established physical laws . In particular, these include the laws of quantum mechanics , electromagnetism and statistical mechanics . The most familiar condensed phases are solids and liquids , while more exotic condensed phases include the superconducting phase exhibited by certain materials at low temperature , the ferromagnetic and antiferromagnetic phases of spins on atomic lattices , and the Bose-Einstein condensate found in cold atomic systems .
In physics , classical mechanics is one of the two major sub-fields of mechanics , which is concerned with the set of physical laws describing the motion of bodies under the action of a system of forces. The study of the motion of bodies is an ancient one, making classical mechanics one of the oldest and largest subjects in science , engineering and technology . Classical mechanics describes the motion of macroscopic objects, from projectiles to parts of machinery , as well as astronomical objects , such as spacecraft , planets , stars , and galaxies . Besides this, many specializations within the subject deal with gases , liquids , solids , and other specific sub-topics.