Slopes Stability

In a sloping soil mass, forces acting on it try to cause the soil mass to move from higher elevation to lower elevation. The forces which try to cause instability are force due to gravity, imposed loads and seepage forces. These forces produce shearing stress in the soil, and unless the shearing resistance of the soil is sufficient to withstand them the slope fails in shear along a well defined failure surface. The safety of a slope against failure is its stability. The failure of a mass of soil located beneath a slope is called a slide. To avoid failure, a thorough analysis is needed else the failure may lead to loss of human life as well as a loss of national economy.

The stability can be determined with a reasonable accuracy, if the geological cross section of the slope and the shear strength parameters of the soil are known. The accuracy of the result depends on the accuracy with which the shear strength is predicted.

Causes of Slope Instability

The causes of slope instability may be due to:

a. Increase in shear strength.

b. Reduction in shear strength.

These may be due to :

1. Gravitational force
2. Force due to seepage of water
3. Erosion of surface due to flowing water
4. The sudden lowering of water adjacent to a slope
5. Forces due to earthquakes

Many slope failures are associated with the exceeding presence of water during heavy rainfall and flood. The introduction of the exceeding water content to the soil contributes to both increases in the shear stresses as well as the reduction in the shear strength due to the increase in the pore water pressure.

Remedial measures for Slope Stability

1. Flattening the slope reduces the weight of the potential sliding mass and consequently the driving force, resulting in the increase of the factor of safety.
2. The presence of a berm adjacent to the toe of the slope increases the resisting forces and consequently the factor of safety will be increased. This is especially useful when there is a possibility of base failure.
3. Proper drainage of water is one of the most effective methods to increase the stability of earth slope. Surface drainage and sub drainage are provided to increase the stability of the slope.
4. Densification of the ground increases the shearing resistance of the soil, thus increases the stability of the slope. a) Addition of chemical additives (lime or cement) for clay soils & b) Vibro-floatation (deep densification of cohesion-less soils)
5. Construction of earth retaining structures (retaining walls, reinforced earth, etc.) at the toe of the slope increases the resistance of the potential sliding mass.
6. Planting the surface of the slope is beneficial to protect the slope against shallow slides. The plants enhance the stability of the slope in two different ways:

• Consolidation of the soil by a network of roots and therefore increasing the resistance to shear.
• Drying out the surface layers by water suction by the roots, increasing the shearing resistance of the soil.

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Index Properties of Soil

Soil can exit in nature in innumerable varieties and these materials do not lend themselves to separate into distinct categories. Proper classification of soil is an important step in connection with any foundation job because it provides the first clue to the experiences that may be anticipated during and after construction. The laboratory tests, which provide information on physical properties of soil, are known as classification tests and numerical results of such tests are known as index properties. If the classification tests are properly chosen, soil materials having similar index properties are likely to exhibit similar engineering behaviour. On the basis of some laboratory tests, it has been found that soil can be classified into groups within each of which the significant engineering properties are somewhat similar.

The index properties are of a great value to the civil engineer in that, in one hand, they provide means in the correlation of construction experience and on the other hand they form a basis for information of the correctness of the field identification of a given material. It the material is improperly identified, the index properties indicate the errors and lead to correct classification. Index properties may be divided into two general types:

1. Soil Grain Properties

2. Soil Aggregate Properties

Soil Grain Properties are the properties of the individual particles of which the soil is composed of and are independent in the manner of soil formation. These properties can be determined from distributed samples. Soil Aggregate Properties, on the other hand, depend on the structure and the arrangement of the particles in the soil mass, whereas the soil grain properties are commonly used for soil identification and classification. The soil aggregate properties have a greater influence on the engineering behaviour of soil mass. The engineering behaviour of a soil mass depends on its strength, compressibility and permeability characteristics. The most important aggregate property of a coarse grained soil is its relative density while that of a fine-grained soil is its consistency.

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Applied Sociology

The science that studies social relationship, social interaction, social process and changes of society is sociology. The term sociology is derived from Latin word 'Socius'/'Societus' which means society and the Greek word 'Logos' which means science or study. Thus the etymological meaning of sociology is science of society or study of society. Simply sociology is the scientific study of human's social behaviour in groups and societies.

The term sociology was first used by French Philosopher Auguste Comte at about 1839 in his famous book 'Positive Philosophy'. First of all he used the term "Social Physics" in spite of sociology and later on he coined the term sociology and defines its scope and methods. So, he is called the father of sociology. Similarly, Herbert Spencer, Emile Durkheim and Max Weber contributed a lot to promote sociology. So they are known 'four founding father' of sociology.

As a social science, sociology always concentrates on the study of social behaviour in groups, social action, social interaction, social relationship, social process and change of society. It studies the ethnic, linguist, gender, cultural, religious, economic and political diversity of society. It attempts to explain the origin, development and change of social institution, social organizations, social structure, social norms and values and their function. The main concern of sociology is to describe ,explain and predict social stability as well as social change or social reality.

Soil Mechanics

The term soil has different definition and important for scientist of different disciplines. For an agriculturist, soil is the topmost layer of the earth responsible for supporting plant life. For a geologist, soil is a thin upper layer of loose sediments within which plant roots are present. For civil engineers, soil means all naturally occurring relatively unconsolidated earth material organic or inorganic in character that lies above the bed rock which is responsible for supporting civil engineering structure.

Soil mechanics involves the study of mechanical behaviour of soil. It is the branch of applied mechanics which deals with the application of mechanics, hydraulics and chemistry. Soil mechanics makes us able to understand soil behaviour and soil problems and become able to design foundation. Satisfactory solution to soil related problems can be proposed after a further study of soil mechanics.

Formation of soil

Soil form from rocks by weathering actions which is either by physical disintegration of chemical decomposition. Soil may be considered as an incidental material obtained from geological cycle which goes on continuously in nature. The cycle consists of erosion, transportation, deposition and upheaval.

Classification of soil

Depending upon the place of deposition, soil may be classified as:

1.  Residual soil:- Also known as sedimentary soil, it resembles its parent property.
2. Transported soil:- Deposited after the transportation by various means, so it lost its parent property.

Earthquake

An earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. The seismicity, seismism or seismic activity of an area refers to the frequency, type and size of earthquakes experienced over a period of time. Earthquakes are measured using observations from seismometers. The moment magnitude is the most common scale on which earthquakes larger than approximately 5 are reported for the entire globe. The more numerous earthquakes smaller than magnitude 5 reported by national seismological observatories are measured mostly on the local magnitude scale, also referred to as the Richter scale. These two scales are numerically similar over their range of validity. Magnitude 3 or lower earthquakes are mostly almost imperceptible and magnitude 7 and over potentially cause serious damage over large areas, depending on their depth. The largest earthquakes in historic times have been of magnitude slightly over 9, although there is no limit to the possible magnitude. The most recent large earthquake of magnitude 9.0 or larger was a 9.0 magnitude earthquake in Japan in 2011 (as of March 2011), and it was the largest Japanese earthquake since records began. Intensity of shaking is measured on the modified Mercalli scale. The shallower an earthquake, the more damage to structures it causes, all else being equal.

At the Earth's surface, earthquakes manifest themselves by shaking and sometimes displacement of the ground. When the epicenter of a large earthquake is located offshore, the seabed may be displaced sufficiently to cause a tsunami. Earthquakes can also trigger landslides, and occasionally volcanic activity.

Tectonic earthquakes occur anywhere in the earth where there is sufficient stored elastic strain energy to drive fracture propagation along a fault plane. The sides of a fault move past each other smoothly and aseismically only if there are no irregularities or asperities along the fault surface that increase the frictional resistance. Most fault surfaces do have such asperities and this leads to a form of stick-slip behaviour. Once the fault has locked, continued relative motion between the plates leads to increasing stress and therefore, stored strain energy in the volume around the fault surface. This continues until the stress has risen sufficiently to break through the asperity, suddenly allowing sliding over the locked portion of the fault, releasing the stored energy. This energy is released as a combination of radiated elastic strain seismic waves, frictional heating of the fault surface, and cracking of the rock, thus causing an earthquake. This process of gradual build-up of strain and stress punctuated by occasional sudden earthquake failure is referred to as the elastic-rebound theory. It is estimated that only 10 percent or less of an earthquake's total energy is radiated as seismic energy. Most of the earthquake's energy is used to power the earthquake fracture growth or is converted into heat generated by friction. Therefore, earthquakes lower the Earth's available elastic potential energy and raise its temperature, though these changes are negligible compared to the conductive and convective flow of heat out from the Earth's deep interior.

Astronomy

Astronomy is a natural science that deals with the study of celestial objects (such as stars, planets, comets, nebulae, star clusters and galaxies) and phenomena that originate outside the atmosphere of Earth (such as the cosmic background radiation). It is concerned with the evolution, physics, chemistry, meteorology, and motion of celestial objects, as well as the formation and development of the universe.

Astronomy is one of the oldest sciences. Prehistoric cultures left behind astronomical artifacts such as the Egyptian monuments, Nubian monuments and Stonehenge, and early civilizations such as the Babylonians, Greeks, Chinese, Indians, Iranians and Maya performed methodical observations of the night sky. However, the invention of the telescope was required before astronomy was able to develop into a modern science. Historically, astronomy has included disciplines as diverse as astrometry, celestial navigation, observational astronomy, the making of calendars, and astrology, but professional astronomy is nowadays often considered to be synonymous with astrophysics.

During the 20th century, the field of professional astronomy split into observational and theoretical branches. Observational astronomy is focused on acquiring data from observations of celestial objects, which is then analyzed using basic principles of physics. Theoretical astronomy is oriented towards the development of computer or analytical models to describe astronomical objects and phenomena. The two fields complement each other, with theoretical astronomy seeking to explain the observational results, and observations being used to confirm theoretical results.

Amateur astronomers have contributed to many important astronomical discoveries, and astronomy is one of the few sciences where amateurs can still play an active role, especially in the discovery and observation of transient phenomena.

Astronomy is not to be confused with astrology, the belief system which claims that human affairs are correlated with the positions of celestial objects. Although the two fields share a common origin they are now entirely distinct.

Geology

Geology (from the Greek geo, "earth" and logos, "study") is the science comprising the study of solid Earth, the rocks of which it is composed, and the processes by which it evolves. Geology gives insight into the history of the Earth, as it provides the primary evidence for plate tectonics, the evolutionary history of life, and past climates. In modern times, geology is commercially important for mineral and hydrocarbon exploration and for evaluating water resources; is publicly important for the prediction and understanding of natural hazards, the remediation of environmental problems, and for providing insights into past climate change; plays an essential role in geotechnical engineering; and is a major academic discipline. Geology is also a hobby for those who enjoy collecting various rocks, minerals and/or fossils.

Geologic materials

The majority of geological data come from research on solid Earth materials. These typically fall into one of two categories: rock and unconsolidated material.

Rock

There are three major types of rock: igneous, sedimentary, and metamorphic. The rock cycle is an important concept in geology which illustrates the relationships between these three types of rock, and magma. When a rock crystallizes from melt (magma and/or lava), it is an igneous rock. This rock can be weathered and eroded, and then redeposited and lithified into a sedimentary rock, or be turned into a metamorphic rock due to heat and pressure that change the mineral content of the rock and give it a characteristic fabric. The sedimentary rock can then be subsequently turned into a metamorphic rock due to heat and pressure, and the metamorphic rock can be weathered, eroded, deposited, and lithified, becoming a sedimentary rock. Sedimentary rock may also be re-eroded and redeposited, and metamorphic rock may also undergo additional metamorphism. All three types of rocks may be re-melted; when this happens, a new magma is formed, from which an igneous rock may once again crystallize.

Unconsolidated material

Geologists also study unlithified material, which typically comes from more recent deposits. Because of this, the study of such material is often known as Quaternary geology, after the recent Quaternary Period. This includes the study of sediment and soils, and is important to some (or many) studies in geomorphology, sedimentology, and paleoclimatology.

Periodic Table

The periodic table of the chemical elements (also known as the periodic table or periodic table of the elements) is a tabular display of the 118 known chemical elements organized by selected properties of their atomic structures. Elements are presented by increasing atomic number, the number of protons in an atom's atomic nucleus. While rectangular in general outline, gaps are included in the horizontal rows (known as periods) as needed to keep elements with similar properties together in vertical columns (known as groups), e.g. alkali metals, alkali earths, halogens, noble gases.

Although there were precursors, the current presentation's invention is generally credited to Russian chemist Dmitri Mendeleev, who developed a version of the now-familiar tabular presentation in 1869 to illustrate recurring ("periodic") trends in the properties of the then-known elements. The layout of the table has been refined and extended over time, as new elements have been discovered, and new theoretical models have been developed to explain chemical behavior.

Since the periodic table accurately predicts the abilities of various elements to combine into chemical compounds, use of the periodic table is now ubiquitous within the academic discipline of chemistry, providing a useful framework to classify, systematize, and compare many of the many different forms of chemical behavior. The table has found many applications not only in chemistry and physics, but also in such diverse fields as geology, biology, materials science, engineering, agriculture, medicine, nutrition, environmental health, and astronomy. Its principles are especially important in chemical engineering.

One of the strengths of Mendeleev's presentation is that the original version accurately predicted some of the properties of then-undiscovered elements expected to fill gaps in his arrangement. For example: "eka-aluminium", expected to have properties intermediate between aluminium and indium, was discovered with said properties in 1875 and named gallium. No gaps remain in the current 118-element periodic table; all elements from hydrogen to plutonium except technetium, promethium and neptunium exist in the Earth in macroscopic or recurrently produced trace quantities. The three said exceptions do exist naturally, but only in trace amounts as the result of rare nuclear processes from decay of heavy elements. Every element through Copernicium, element 112, has been isolated, characterized, and named, and elements 113 through 118 have been synthesized in laboratories around the world.

While plutonium is now included among the 91 regularly occurring natural elements, and technetium, promethium, and neptunium also occur naturally in transient trace amounts, these four elements were first identified and characterized from technologically produced samples. Numerous synthetic radionuclides of various naturally occurring elements have been produced as well.

Electricity

Electricity is a general term encompassing a variety of phenomena resulting from the presence and flow of electric charge. These include many easily recognizable phenomena, such as lightning, static electricity, and the flow of electrical current in an electrical wire. In addition, electricity encompasses less familiar concepts such as the electromagnetic field and electromagnetic induction.

The word is from the New Latin ēlectricus, "amber-like"[a], coined in the year 1600 from the Greek electron meaning amber (hardened plant resin), because electrical effects were produced classically by rubbing amber.

Electronics

Electronics is the branch of science, engineering and technology that deals with electrical circuits involving active electrical components such as vacuum tubes, transistors, diodes and integrated circuits, and associated passive interconnection technologies. The nonlinear behaviour of active components and their ability to control electron flows makes amplification of weak signals possible and is usually applied to information and signal processing. Similarly, the ability of electronic devices to act as switches makes digital information processing possible. Interconnection technologies such as circuit boards, electronics packaging technology, and other varied forms of communication infrastructure complete circuit functionality and transform the mixed components into a working system.

Electronics is distinct from electrical and electro-mechanical science and technology, which deals with the generation, distribution, switching, storage and conversion of electrical energy to and from other energy forms using wires, motors, generators, batteries, switches, relays, transformers, resistors and other passive components. This distinction started around 1906 with the invention by Lee De Forest of the triode, which made electrical amplification of weak radio signals and audio signals possible with a non-mechanical device. Until 1950 this field was called "radio technology" because its principal application was the design and theory of radio transmitters, receivers and vacuum tubes.

Today, most electronic devices use semiconductor components to perform electron control. The study of semiconductor devices and related technology is considered a branch of solid state physics, whereas the design and construction of electronic circuits to solve practical problems come under electronics engineering. This article focuses on engineering aspects of electronics.

Thermodynamics

Thermodynamics is a physical science that studies the effects on material bodies, and on radiation in regions of space, of transfer of heat and of work done on or by the bodies or radiation. It interrelates macroscopic variables, such as temperature, volume and pressure, which describe physical properties of material bodies and radiation, which in this science are called thermodynamic systems.

Historically, thermodynamics developed out of a desire to increase the efficiency of early steam engines, particularly through the work of French physicist Nicolas Léonard Sadi Carnot (1824) who believed that the efficiency of heat engines was the key that could help France win the Napoleonic Wars. Scottish physicist Lord Kelvin was the first to formulate a concise definition of thermodynamics in 1854:

Thermo-dynamics is the subject of the relation of heat to forces acting between contiguous parts of bodies, and the relation of heat to electrical agency.

Initially, the thermodynamics of heat engines concerned mainly the thermal properties of their 'working materials', such as steam. This concern was then linked to the study of energy transfers in chemical processes, for example to the investigation, published in 1840, of the heats of chemical reactions[3] by Germain Hess, which was not originally explicitly concerned with the relation between energy exchanges by heat and work. Chemical thermodynamics studies the role of entropy in chemical reactions. Also, statistical thermodynamics, or statistical mechanics, gave explanations of macroscopic thermodynamics by statistical predictions of the collective motion of particles based on the mechanics of their microscopic behavior.

Thermodynamics describes how systems change when they interact with one another or with their surroundings. This can be applied to a wide variety of topics in science and engineering, such as engines, phase transitions, chemical reactions, transport phenomena, and even black holes. The results of thermodynamics are essential for other fields of physics and for chemistry, chemical engineering, aerospace engineering, mechanical engineering, cell biology, biomedical engineering, materials science, and are useful for other fields such as economics.

Many of the empirical facts of thermodynamics are comprehended in its four laws. The first law specifies that energy can be exchanged between physical systems as heat and thermodynamic work. The second law concerns a quantity called entropy, that expresses limitations, arising from what is known as irreversibility, on the amount of thermodynamic work that can be delivered to an external system by a thermodynamic process. Many writers offer various axiomatic formulations of thermodynamics, as if it were a completed subject, but non-equilibrium processes continue to make difficulties for it.

Engineering

Engineering is the discipline, art, skill and profession of acquiring and applying scientific, mathematical, economic, social, and practical knowledge, in order to design and build structures, machines, devices, systems, materials and processes.

The American Engineers' Council for Professional Development (ECPD, the predecessor of ABET) has defined "engineering" as:

the creative application of scientific principles to design or develop structures, machines, apparatus, or manufacturing processes, or works utilizing them singly or in combination; or to construct or operate the same with full cognizance of their design; or to forecast their behavior under specific operating conditions; all as respects an intended function, economics of operation and safety to life and property.

One who practices engineering is called an engineer, and those licensed to do so may have more formal designations such as Professional Engineer, Chartered Engineer, Incorporated Engineer, Ingenieur or European Engineer. The broad discipline of engineering encompasses a range of more specialized sub disciplines, each with a more specific emphasis on certain fields of application and particular areas of technology.

Biology

Biology is a natural science concerned with the study of life and living organisms, including their structure, function, growth, origin, evolution, distribution, and taxonomy. Biology is a vast subject containing many subdivisions, topics, and disciplines. Among the most important topics are five unifying principles that can be said to be the fundamental axioms of modern biology:

1. Cells are the basic unit of life.

2. New species and inherited traits are the product of evolution.

3. Genes are the basic unit of heredity.

4. An organism regulates its internal environment to maintain a stable and constant condition.

5. Living organisms consume and transform energy.

Subdisciplines of biology are recognized on the basis of the scale at which organisms are studied and the methods used to study them: biochemistry examines the rudimentary chemistry of life; molecular biology studies the complex interactions of systems of biological molecules; cellular biology examines the basic building block of all life, the cell; physiology examines the physical and chemical functions of the tissues, organs, and organ systems of an organism; and ecology examines how various organisms interact and associate with their environment.

Branches of biology

These are the main branches of biology:

1. Aerobiology — the study of airborne organic particles

2. Agriculture — the study of producing crops from the land, with an emphasis on practical applications

3. Anatomy — the study of form and function, in plants, animals, and other organisms, or specifically in humans

4. Arachnology — the study of arachnids

5. Astrobiology — the study of evolution, distribution, and future of life in the universe—also known as exobiology, exopaleontology, and bioastronomy

6. Biochemistry — the study of the chemical reactions required for life to exist and function, usually a focus on the cellular level

7. Bioengineering — the study of biology through the means of engineering with an emphasis on applied knowledge and especially related to biotechnology

8. Biogeography — the study of the distribution of species spatially and temporally

9. Bioinformatics — the use of information technology for the study, collection, and storage of genomic and other biological data

10. Biomathematics or Mathematical Biology — the quantitative or mathematical study of biological processes, with an emphasis on modeling

11. Biomechanics — often considered a branch of medicine, the study of the mechanics of living beings, with an emphasis on applied use through prosthetics or orthotics

12. Biomedical research — the study of the human body in health and disease

13. Biophysics — the study of biological processes through physics, by applying the theories and methods traditionally used in the physical sciences

14. Biotechnology — a new and sometimes controversial branch of biology that studies the manipulation of living matter, including genetic modification and synthetic biology

15. Building biology — the study of the indoor living environment

16. Botany — the study of plants

17. Cell biology — the study of the cell as a complete unit, and the molecular and chemical interactions that occur within a living cell

18. Conservation Biology — the study of the preservation, protection, or restoration of the natural environment, natural ecosystems, vegetation, and wildlife

19. Cryobiology — the study of the effects of lower than normally preferred temperatures on living beings.

20. Developmental biology — the study of the processes through which an organism forms, from zygote to full structure

21. Ecology — the study of the interactions of living organisms with one another and with the non-living elements of their environment

22. Embryology — the study of the development of embryo (from fecundation to birth). See also topobiology.

23. Entomology — the study of insects

24. Environmental Biology — the study of the natural world, as a whole or in a particular area, especially as affected by human activity

25. Epidemiology — a major component of public health research, studying factors affecting the health of populations

26. Ethology — the study of animal behavior

27. Evolutionary Biology — the study of the origin and descent of species over time

28. Genetics — the study of genes and heredity

29. Herpetology — the study of reptiles and amphibians

30. Histology — the study of cells and tissues, a microscopic branch of anatomy

31. Ichthyology — the study of fish

32. Integrative biology — the study of whole organisms

33. Limnology — the study of inland waters

34. Mammalogy — the study of mammals

35. Marine Biology — the study of ocean ecosystems, plants, animals, and other living beings

36. Microbiology — the study of microscopic organisms (microorganisms) and their interactions with other living things

37. Molecular Biology — the study of biology and biological functions at the molecular level, some cross over with biochemistry

38. Mycology — the study of fungi

39. Neurobiology — the study of the nervous system, including anatomy, physiology and pathology

40. Oceanography — the study of the ocean, including ocean life, environment, geography, weather, and other aspects influencing the ocean

41. Oncology — the study of cancer processes, including virus or mutation oncogenesis, angiogenesis and tissues remoldings

42. Ornithology — the study of birds

43. Population biology — the study of groups of conspecific organisms, including

     a. Population ecology — the study of how population dynamics and extinction

     b. Population genetics — the study of changes in gene frequencies in populations of organisms

44. Paleontology — the study of fossils and sometimes geographic evidence of prehistoric life

45. Pathobiology or pathology — the study of diseases, and the causes, processes, nature, and development of disease

46. Parasitology — the study of parasites and parasitism

47. Pharmacology — the study and practical application of preparation, use, and effects of drugs and synthetic medicines

48. Physiology — the study of the functioning of living organisms and the organs and parts of living organisms

49. Phytopathology — the study of plant diseases (also called Plant Pathology)

50. Psychobiology — the study of the biological bases of psychology

51. Sociobiology — the study of the biological bases of sociology

52. Structural biology — a branch of molecular biology, biochemistry, and biophysics concerned with the molecular structure of biological macromolecules

53. Virology — the study of viruses and some other virus-like agents

54. Zoology — the study of animals, including classification, physiology, development, and behavior (See also Entomology, Ethology, Herpetology, Ichthyology, Mammalogy, and Ornithology)

Physics

Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.

Physics is one of the oldest academic disciplines, perhaps the oldest through its inclusion of astronomy. Over the last two millennia, physics was a part of natural philosophy along with chemistry, certain branches of mathematics, and biology, but during the Scientific Revolution in the 16th century, the natural sciences emerged as unique research programs in their own right. Physics intersects with many interdisciplinary areas of research, such as biophysics and quantum chemistry, and the boundaries of physics are not rigidly defined. Indeed, new ideas in physics often explain the fundamental mechanisms of other sciences, while opening new avenues of research in areas such as mathematics and philosophy.

Physics also makes significant contributions through advances in new technologies that arise from theoretical breakthroughs. For example, advances in the understanding of electromagnetism or nuclear physics led directly to the development of new products which have dramatically transformed modern-day society, such as television, computers, domestic appliances, and nuclear weapons; advances in thermodynamics led to the development of industrialization; and advances in mechanics inspired the development of calculus.

Fundamental physics

While physics aims to discover universal laws, its theories lie in explicit domains of applicability. Loosely speaking, the laws of classical physics accurately describe systems whose important length scales are greater than the atomic scale and whose motions are much slower than the speed of light. Outside of this domain, observations do not match their predictions. Albert Einstein contributed the framework of special relativity, which replaced notions of absolute time and space with spacetime and allowed an accurate description of systems whose components have speeds approaching the speed of light. Max Planck, Erwin Schrödinger, and others introduced quantum mechanics, a probabilistic notion of particles and interactions that allowed an accurate description of atomic and subatomic scales. Later, quantum field theory unified quantum mechanics and special relativity. General relativity allowed for a dynamical, curved spacetime, with which highly massive systems and the large-scale structure of the universe can be well described. General relativity has not yet been unified with the other fundamental descriptions; several candidates theories of quantum gravity are being developed.

Physics is a branch of fundamental science, not practical science. Physics is also called "the fundamental science" because the subject of study of all branches of natural science like Chemistry, Astronomy, Geology and Biology are constrained by laws of physics. For example, Chemistry studies properties, structures, and reactions of matter (chemistry's focus on the atomic scale distinguishes it from physics). Structures are formed because particles exert electrical forces on each other, properties include physical characteristics of given substances, and reactions are bound by laws of physics, like conservation of energy, mass and charge.

Physics is applied in industries like engineering and medicine.

Chemistry

Chemistry is the science of matter, especially its chemical reactions, but also its composition, structure and properties.Chemistry is concerned with atoms and their interactions with other atoms, and particularly with the properties of chemical bonds.

Chemistry is sometimes called "the central science" because it connects physics with other natural sciences such as geology and biology.Chemistry is a branch of physical science but distinct from physics.

The etymology of the word chemistry has been much disputed.The genesis of chemistry can be traced to certain practices, known as alchemy, which had been practiced for several millennia in various parts of the world, particularly the Middle East.

The word chemistry comes from the word alchemy, an earlier set of practices that encompassed elements of chemistry, metallurgy, philosophy, astrology, astronomy, mysticism and medicine; it is commonly thought of as the quest to turn lead or another common starting material into gold. The word alchemy in turn is derived from the Arabic word al-kīmīā, meaning alchemy.

The word al-kīmīā is derived from the word Chemi or Kimi, which is the ancient name of Egypt in Egyptian. An alchemist was called a 'chemist' in popular speech, and later the suffix "-ry" was added to this to describe the art of the chemist as "chemistry".

Chemistry can be categorized into three parts:

1. Physical Chemistry

2. Inorganic Chemistry

3. Organic Chemistry

Several concepts are necessary to understand the chemistry.