i need help in my assignment in physics class?

Question

can you pls help me me here are the questions:
1. what is physics?
2. what are the sub - area of physics?
3 how phsics help in technological developments?

Answer 1

Physics (from the Greek, φύσις (phúsis), "nature" and φυσική (phusiké), "knowledge of nature") is the science concerned with the discovery and understanding of the fundamental laws which govern matter, energy, space and time. That is, physics deals with the elementary constituents of the Universe and their interactions, as well as the analysis of systems which are best understood in terms of these fundamental principles. Physics is a study of the inorganic, physical world, as opposed to the organic world of biology, physiology, etc. [1] Physics overlaps with chemistry concerning the electro-chemical interactions of substances.
Central theories

While physics deals with a wide variety of systems, there are certain theories that are used by all physicists. Each of these theories were experimentally tested numerous times and found correct as an approximation of nature (within a certain domain of validity). For instance, the theory of classical mechanics accurately describes the motion of objects, provided they are much larger than atoms and moving at much less than the speed of light. These theories continue to be areas of active research; for instance, a remarkable aspect of classical mechanics known as chaos was discovered in the 20th century, three centuries after the original formulation of classical mechanics by Isaac Newton (1642–1727). These "central theories" are important tools for research into more specialized topics, and any physicist, regardless of his or her specialization, is expected to be literate in them.

* Classical mechanics is a model of the physics of forces acting upon bodies. It is often referred to as "Newtonian mechanics" after Newton and his laws of motion. Classical mechanics is subdivided into statics (which models objects at rest), kinematics (which models objects in motion), and dynamics (which models objects subjected to forces). See also mechanics.

* Electromagnetism, or electromagnetic theory, is the physics of the electromagnetic field: a field, encompassing all of space, which exerts a force on those particles that possess the property of electric charge, and is in turn affected by the presence and motion of such particles. Electromagnetism encompasses various real-world electromagnetic phenomena.

* Thermodynamics is the branch of physics that deals with the action of heat and the conversions from one to another of various forms of energy. Thermodynamics is particularly concerned with how these affect temperature, pressure, volume, mechanical action, and work. Historically, it grew out of efforts to construct more efficient heat engines — devices for extracting useful work from expanding hot gases.

* Statistical mechanics, a related theory, is the branch of physics that analyzes macroscopic systems by applying statistical principles to their microscopic constituents and, thus, can be used to calculate the thermodynamic properties of bulk materials from the spectroscopic data of individual molecules.

* Quantum mechanics is the branch of mathematical physics treating atomic and subatomic systems and their interaction with radiation in terms of observable quantities. It is based on the observation that all forms of energy are released in discrete units or bundles called quanta. Quantum theory typically permits only probable or statistical calculation of the observed features of subatomic particles, understood in terms of wave functions.

* The theory of relativity, or relativity theory, is:

*
o A physical theory which is based on two postulates (1) that the speed of light in a vacuum is constant and independent of the source or observer and (2) that it is impossible to determine ones absolute velocity in any inertial systems and which leads to the deduction of the equivalence of mass and energy and of change in mass, dimension, and time with increased velocity — called also special relativity, special theory of relativity;
o An extension of the theory to include gravitation and related acceleration phenomena — called also general relativity, general theory of relativity.

Major fields of physics

Contemporary research in physics is divided into several distinct fields that study different aspects of the material world.

* Condensed matter physics, by most estimates the largest single field of physics, is concerned with how the properties of bulk matter, such as the ordinary solids and liquids we encounter in everyday life, arise from the properties and mutual interactions of the constituent atoms. A magnet levitating above a high-temperature superconductor (with boiling liquid nitrogen underneath), demonstrating the Meissner effect, is a phenomenon of importance to the field of condensed matter physics.

* The field of atomic, molecular, and optical physics deals with the behavior of individual atoms and molecules, and in particular the ways in which they absorb and emit light.

* The field of particle physics, also known as "high-energy physics", is concerned with the properties of submicroscopic particles much smaller than atoms, including the elementary particles from which all other units of matter are constructed.

* Finally, the field of astrophysics applies the laws of physics to explain celestial phenomena, ranging from the Sun and the other objects in the solar system to the Universe as a whole.

Since the 20th century, the individual fields of physics have become increasingly specialized, and nowadays it is not uncommon for physicists to work in a single field for their entire careers. "Universalists" like Albert Einstein (1879–1955) and Lev Landau (1908–1968), who were comfortable working in multiple fields of physics, are now very rare.

Answer 2

Physics is an attempt to describe the properties of the physical universe. All of them.

Sub-areas: mechanics, electricity and magnetism, optics, thermodynamics, fluid mechanics (including aerodynamics), quantum mechanics, quantum electrodynamics, quantum optics, relativity, statistical mechanics, plasmas, atomic physics, nuclear physics, solid state physics, circuits, particle physics, astrophysics. These are the ones that came to mind.

Physics allows for very accurate predictions from theoretical models. This means that a person can work out a system on paper and be able to predict, often very accurately, what will happen in the physical world. Most of the world's inventions have involved a consideration of physical laws for their creation.

Answer 3

1. Is the science that explain all nature
2. Atomical, nuclear, electromagnetic, mechanical.
3. All new devices are based in quantum physics: tunnel effect, spin polarization, etc.

Answer 4

You'll definitely get the answers to your first two questions from this link. They also talk about applied physics and have other links. Good luck with your assignment.

http://en.wikipedia.org/wiki/Physics

Answer 5

http://www.sc.doe.gov/Sub/Newsroom/News_Releases/DOE-SC/2005/What_is_Physics.htm Try this site..let me know if it helps. =)

Answer 6

Physics (from the Greek, φύσις (phúsis), "nature" and φυσική (phusiké), "knowledge of nature") is the science concerned with the discovery and understanding of the fundamental laws which govern matter, energy, space and time. That is, physics deals with the elementary constituents of the Universe and their interactions, as well as the analysis of systems which are best understood in terms of these fundamental principles. Physics is a study of the inorganic, physical world, as opposed to the organic world of biology, physiology, etc. [1] Physics overlaps with chemistry concerning the electro-chemical interactions of substances.

Classical mechanics is a model of the physics of forces acting upon bodies. It is often referred to as "Newtonian mechanics" after Newton and his laws of motion. Classical mechanics is subdivided into statics (which models objects at rest), kinematics (which models objects in motion), and dynamics (which models objects subjected to forces). See also mechanics.
Electromagnetism, or electromagnetic theory, is the physics of the electromagnetic field: a field, encompassing all of space, which exerts a force on those particles that possess the property of electric charge, and is in turn affected by the presence and motion of such particles. Electromagnetism encompasses various real-world electromagnetic phenomena.
Thermodynamics is the branch of physics that deals with the action of heat and the conversions from one to another of various forms of energy. Thermodynamics is particularly concerned with how these affect temperature, pressure, volume, mechanical action, and work. Historically, it grew out of efforts to construct more efficient heat engines — devices for extracting useful work from expanding hot gases.
Statistical mechanics, a related theory, is the branch of physics that analyzes macroscopic systems by applying statistical principles to their microscopic constituents and, thus, can be used to calculate the thermodynamic properties of bulk materials from the spectroscopic data of individual molecules.
Quantum mechanics is the branch of mathematical physics treating atomic and subatomic systems and their interaction with radiation in terms of observable quantities. It is based on the observation that all forms of energy are released in discrete units or bundles called quanta. Quantum theory typically permits only probable or statistical calculation of the observed features of subatomic particles, understood in terms of wave functions.
The theory of relativity, or relativity theory, is:

A physical theory which is based on two postulates (1) that the speed of light in a vacuum is constant and independent of the source or observer and (2) that it is impossible to determine ones absolute velocity in any inertial systems and which leads to the deduction of the equivalence of mass and energy and of change in mass, dimension, and time with increased velocity — called also special relativity, special theory of relativity;
An extension of the theory to include gravitation and related acceleration phenomena — called also general relativity, general theory of relativity.

Major fields of physics
Contemporary research in physics is divided into several distinct fields that study different aspects of the material world.

Condensed matter physics, by most estimates the largest single field of physics, is concerned with how the properties of bulk matter, such as the ordinary solids and liquids we encounter in everyday life, arise from the properties and mutual interactions of the constituent atoms. A magnet levitating above a high-temperature superconductor (with boiling liquid nitrogen underneath), demonstrating the Meissner effect, is a phenomenon of importance to the field of condensed matter physics.
The field of atomic, molecular, and optical physics deals with the behavior of individual atoms and molecules, and in particular the ways in which they absorb and emit light.
The field of particle physics, also known as "high-energy physics", is concerned with the properties of submicroscopic particles much smaller than atoms, including the elementary particles from which all other units of matter are constructed.
Finally, the field of astrophysics applies the laws of physics to explain celestial phenomena, ranging from the Sun and the other objects in the solar system to the Universe as a whole.
Since the 20th century, the individual fields of physics have become increasingly specialized, and nowadays it is not uncommon for physicists to work in a single field for their entire careers. "Universalists" like Albert Einstein (1879–1955) and Lev Landau (1908–1968), who were comfortable working in multiple fields of physics, are now very rare.

[edit] Classical, quantum and modern physics
Further information: Classical physics, Quantum physics, Modern physics, Semiclassical
Since the construction of quantum mechanics in the early twentieth century, it generally became evident to the physical community that it would be preferable for many known descriptions of nature to be quantized, that is, to follow the postulates of quantum mechanics. To this effect, all results that were not quantized are called classical: this includes the Special Theory and General Theory of Relativity. Simply because a result is classical does not mean that it was discovered before the advent of quantum mechanics. Classical theories are, generally, much easier to work with and much research is still being conducted on them without the express aim of quantization. However, there exist problems in physics in which classical and quantum aspects must be combined to attain some approximation or limit that may acquire several forms as the passage from classical to quantum mechanics is often difficult — such problems are termed semiclassical.

However, because relativity and quantum mechanics provide the most complete known description of fundamental interactions, and because the changes brought by these two frameworks to the physicist's world view were revolutionary, the term modern physics is used to describe physics which relies on these two theories. Colloquially, modern physics can be described as the physics of extremes: from systems at the extremely small (atoms, nuclei, fundamental particles) to the extremely large (the Universe) and of the extremely fast (relativity).


[edit] Theoretical and experimental physics
The culture of physics research differs from the other sciences in the separation of theory and experiment. Since the 20th century, most individual physicists have specialized in either theoretical physics or experimental physics. The great Italian physicist Enrico Fermi (1901–1954), who made fundamental contributions to both theory and experimentation in nuclear physics, was a notable exception. In contrast, almost all the successful theorists in biology and chemistry (e.g. American quantum chemist and biochemist Linus Pauling) have also been experimentalists, though this is changing as of late.

Roughly speaking, theorists seek to develop through abstractions and mathematical models theories that can both describe and interpret existing experimental results and successfully predict future results, while experimentalists devise and perform experiments to explore new phenomena and test theoretical predictions. Although theory and experiment are developed separately, they are strongly dependent on each other. However, theoretical research in physics may further be considered to draw from mathematical physics and computational physics in addition to experimentation. Progress in physics frequently comes about when experimentalists make a discovery that existing theories cannot account for, necessitating the formulation of new theories. Likewise, ideas arising from theory often inspire new experiments. In the absence of experiment, theoretical research can go in the wrong direction; this is one of the criticisms that has been leveled against M-theory, a popular theory in high-energy physics for which no practical experimental test has ever been devised.

[edit] Applied physics
Applied physics is physics that is intended for a particular technological or practical use, as for example in engineering, as opposed to basic research. This approach is similar to that of applied mathematics. Applied physics is rooted in the fundamental truths and basic concepts of the physical sciences but is concerned with the utilization of scientific principles in practical devices and systems, and in the application of physics in other areas of science. "Applied" is distinguished from "pure" by a subtle combination of factors such as the motivation and attitude of researchers and the nature of the relationship to the technology or science that may be affected by the work

[edit] History
Main article: History of physics
Further information: Famous physicists, Nobel Prize in physics
Since antiquity, people have tried to understand the behavior of matter: why unsupported objects drop to the ground, why different materials have different properties, and so forth. The character of the Universe was also a mystery, for instance the Earth and the behavior of celestial objects such as the Sun and the Moon. Several theories were proposed, most of which were wrong. These first theories were largely couched in philosophical terms, and never verified by systematic experimental testing as is popular today. The works of Ptolemy and Aristotle, however, were also not always found to match everyday observations. There were exceptions and there are anachronisms - for example, Indian philosophers and astronomers gave many correct descriptions in atomism and astronomy, and the Greek thinker Archimedes derived many correct quantitative descriptions of mechanics and hydrostatics.

The willingness to question previously held truths and search for new answers eventually resulted in a period of major scientific advancements, now known as the Scientific Revolution of the late 17th century. The precursors to the scientific revolution can be traced back to the important developments made in India and Persia, including the elliptical model of the planets based on the heliocentric solar system of gravitation developed by Indian mathematician-astronomer Aryabhata; the basic ideas of atomic theory developed by Hindu and Jaina philosophers; the theory of light being equivalent to energy particles developed by the Indian Buddhist scholars Dignāga and Dharmakirti; the optical theory of light developed by Muslim scientist Ibn al-Haitham (Alhazen); the Astrolabe invented by the Persian astronomer Muhammad al-Fazari; and the significant flaws in the Ptolemaic system pointed out by Persian scientist Nasir al-Din Tusi.

As the influence of the Arab Empire expanded to Europe, the works of Aristotle preserved by the Arabs, and the works of the Indians and Persians, became known in Europe by the 12th and 13th centuries. This eventually led to the scientific revolution which culminated with the publication of the Philosophiae Naturalis Principia Mathematica in 1687 by the mathematician, physicist, alchemist and inventor Sir Isaac Newton (1643-1727).

The Scientific Revolution is held by most historians (e.g., Howard Margolis) to have begun in 1543, when the first printed copy of Nicolaus Copernicus's De Revolutionibus (most of which had been written years prior but whose publication had been delayed) was brought to the influential Polish astronomer from Nuremberg.

Further significant advances were made over the following century by Galileo Galilei, Christiaan Huygens, Johannes Kepler, and Blaise Pascal. During the early 17th century, Galileo pioneered the use of experimentation to validate physical theories, which is the key idea in modern scientific method. Galileo formulated and successfully tested several results in dynamics, in particular the Law of Inertia. In 1687, Newton published the Principia, detailing two comprehensive and successful physical theories: Newton's laws of motion, from which arise classical mechanics; and Newton's Law of Gravitation, which describes the fundamental force of gravity. Both theories agreed well with experiment. The Principia also included several theories in fluid dynamics. Classical mechanics was re-formulated and extended by Leonhard Euler, French mathematician Joseph-Louis Comte de Lagrange, Irish mathematical physicist William Rowan Hamilton, and others, who produced new results in mathematical physics. The law of universal gravitation initiated the field of astrophysics, which describes astronomical phenomena using physical theories.

After Newton defined classical mechanics, the next great field of inquiry within physics was the nature of electricity. Observations in the 17th and 18th century by scientists such as Robert Boyle, Stephen Gray, and Benjamin Franklin created a foundation for later work. These observations also established our basic understanding of electrical charge and current.

In 1821, the English physicist and chemist Michael Faraday integrated the study of magnetism with the study of electricity. This was done by demonstrating that a moving magnet induced an electric current in a conductor. Faraday also formulated a physical conception of electromagnetic fields. James Clerk Maxwell built upon this conception, in 1864, with an interlinked set of 20 equations that explained the interactions between electric and magnetic fields. These 20 equations were later reduced, using vector calculus, to a set of four equations by Oliver Heaviside.

In addition to other electromagnetic phenomena, Maxwell's equations also can be used to describe light. Confirmation of this observation was made with the 1888 discovery of radio by Heinrich Hertz and in 1895 when Wilhelm Roentgen detected X rays. The ability to describe light in electromagnetic terms helped serve as a springboard for Albert Einstein's publication of the theory of special relativity in 1905. This theory combined classical mechanics with Maxwell's equations. The theory of special relativity unifies space and time into a single entity, spacetime. Relativity prescribes a different transformation between reference frames than classical mechanics; this necessitated the development of relativistic mechanics as a replacement for classical mechanics. In the regime of low (relative) velocities, the two theories agree. Einstein built further on the special theory by including gravity into his calculations, and published his theory of general relativity in 1915.

One part of the theory of general relativity is Einstein's field equation. This describes how the stress-energy tensor creates curvature of spacetime and forms the basis of general relativity. Further work on Einstein's field equation produced results which predicted the Big Bang, black holes, and the expanding universe. Einstein believed in a static universe and tried (and failed) to fix his equation to allow for this. However, by 1929 Edwin Hubble's astronomical observations suggested that the universe is expanding.

From the late 17th century onwards, thermodynamics was developed by physicist and chemist Boyle, Young, and many others. In 1733, Bernoulli used statistical arguments with classical mechanics to derive thermodynamic results, initiating the field of statistical mechanics. In 1798, Thompson demonstrated the conversion of mechanical work into heat, and in 1847 Joule stated the law of conservation of energy, in the form of heat as well as mechanical energy. Ludwig Boltzmann, in the 19th century, is responsible for the modern form of statistical mechanics.

In 1895, Röntgen discovered X-rays, which turned out to be high-frequency electromagnetic radiation. Radioactivity was discovered in 1896 by Henri Becquerel, and further studied by Marie Curie, Pierre Curie, and others. This initiated the field of nuclear physics.

In 1897, Joseph J. Thomson discovered the electron, the elementary particle which carries electrical current in circuits. In 1904, he proposed the first model of the atom, known as the plum pudding model. (The existence of the atom had been proposed in 1808 by John Dalton.)

These discoveries revealed that the assumption of many physicists that atoms were the basic unit of matter was flawed, and prompted further study into the structure of atoms.

In 1911, Ernest Rutherford deduced from scattering experiments the existence of a compact atomic nucleus, with positively charged constituents dubbed protons. Neutrons, the neutral nuclear constituents, were discovered in 1932 by Chadwick. The equivalence of mass and energy (Einstein, 1905) was spectacularly demonstrated during World War II, as research was conducted by each side into nuclear physics, for the purpose of creating a nuclear bomb. The German effort, led by Heisenberg, did not succeed, but the Allied Manhattan Project reached its goal. In America, a team led by Fermi achieved the first man-made nuclear chain reaction in 1942, and in 1945 the world's first nuclear explosive was detonated at Trinity site, near Alamogordo, New Mexico.

In 1900, Max Planck published his explanation of blackbody radiation. This equation assumed that radiators are quantized, which proved to be the opening argument in the edifice that would become quantum mechanics. By introducing discrete energy levels, Planck, Einstein, Niels Bohr, and others developed quantum theories to explain various anomalous experimental results. Quantum mechanics was formulated in 1925 by Heisenberg and in 1926 by Schrödinger and Paul Dirac, in two different ways that both explained the preceding heuristic quantum theories. In quantum mechanics, the outcomes of physical measurements are inherently probabilistic; the theory describes the calculation of these probabilities. It successfully describes the behavior of matter at small distance scales. During the 1920s Schrödinger, Heisenberg, and Max Born were able to formulate a consistent picture of the chemical behavior of matter, a complete theory of the electronic structure of the atom, as a byproduct of the quantum theory.

Quantum field theory was formulated in order to extend quantum mechanics to be consistent with special relativity. It was devised in the late 1940s with work by Richard Feynman, Julian Schwinger, Sin-Itiro Tomonaga, and Freeman Dyson. They formulated the theory of quantum electrodynamics, which describes the electromagnetic interaction, and successfully explained the Lamb shift. Quantum field theory provided the framework for modern particle physics, which studies fundamental forces and elementary particles.

Chen Ning Yang and Tsung-Dao Lee, in the 1950s, discovered an unexpected asymmetry in the decay of a subatomic particle. In 1954, Yang and Robert Mills then developed a class of gauge theories which provided the framework for understanding the nuclear forces (Yang, Mills 1954). The theory for the strong nuclear force was first proposed by Murray Gell-Mann. The electroweak force, the unification of the weak nuclear force with electromagnetism, was proposed by Sheldon Lee Glashow, Abdus Salam and Steven Weinberg and confirmed in 1964 by James Watson Cronin and Val Fitch. This led to the so-called Standard Model of particle physics in the 1970s, which successfully describes all the elementary particles observed to date.

Quantum mechanics also provided the theoretical tools for condensed matter physics, whose largest branch is solid state physics. It studies the physical behavior of solids and liquids, including phenomena such as crystal structures, semiconductivity, and superconductivity. The pioneers of condensed matter physics include Felix Bloch, who created a quantum mechanical description of the behavior of electrons in crystal structures in 1928. The transistor was developed by physicists John Bardeen, Walter Houser Brattain and William Bradford Shockley in 1947 at Bell Telephone Laboratories.

The two themes of the 20th century, general relativity and quantum mechanics, appear inconsistent with each other. General relativity describes the universe on the scale of planets and solar systems while quantum mechanics operates on sub-atomic scales. This challenge is being attacked by string theory, which treats spacetime as composed, not of points, but of one-dimensional objects, strings. Strings have properties like a common string (e.g., tension and vibration). The theories yield promising, but not yet testable results. The search for experimental verification of string theory is in progress.

The United Nations declared the year 2005, the centenary of Einstein's annus mirabilis, as the World Year of Physics.


[edit] Future directions
Main article: Unsolved problems in physics
Research in physics is progressing constantly on a large number of fronts, and is likely to do so for the foreseeable future.

In condensed matter physics, the biggest unsolved theoretical problem is the explanation for high-temperature superconductivity. Strong efforts, largely experimental, are being put into making workable spintronics and quantum computers.

In particle physics, the first pieces of experimental evidence for physics beyond the Standard Model have begun to appear. Foremost amongst these are indications that neutrinos have non-zero mass. These experimental results appear to have solved the long-standing solar neutrino problem in solar physics. The physics of massive neutrinos is currently an area of active theoretical and experimental research. In the next several years, particle accelerators will begin probing energy scales in the TeV range, in which experimentalists are hoping to find evidence for the Higgs boson and supersymmetric particles.

Theoretical attempts to unify quantum mechanics and general relativity into a single theory of quantum gravity, a program ongoing for over half a century, have not yet borne fruit. The current leading candidates are M-theory, superstring theory and loop quantum gravity.

Many astronomical and cosmological phenomena have yet to be satisfactorily explained, including the existence of ultra-high energy cosmic rays, the baryon asymmetry, the acceleration of the universe and the anomalous rotation rates of galaxies.

Although much progress has been made in high-energy, quantum, and astronomical physics, many everyday phenomena, involving complexity, chaos, or turbulence are still poorly understood. Complex problems that seem like they could be solved by a clever application of dynamics and mechanics, such as the formation of sandpiles, nodes in trickling water, the shape of water droplets, mechanisms of surface tension catastrophes, or self-sorting in shaken heterogeneous collections are unsolved. These complex phenomena have received growing attention since the 1970s for several reasons, not least of which has been the availability of modern mathematical methods and computers which enabled complex systems to be modeled in new ways. The interdisciplinary relevance of complex physics has also increased, as exemplified by the study of turbulence in aerodynamics or the observation of pattern formation in biological systems. In 1932, Horace Lamb correctly prophesied the success of the theory of quantum electrodynamics and the near-stagnant progress in the study of turbulence:

I am an old man now, and when I die and go to heaven there are two matters on which I hope for enlightenment. One is quantum electrodynamics, and the other is the turbulent motion of fluids. And about the former I am rather optimistic.