angular momentum

The speed of rotation is given by the angular frequency (rad/s) or frequency / rotational speed / revolutions per minute (turns/s, turns/min), or period (seconds, days, etc.). With one direction of rotation considered positive, the sign of the angular frequency indicates the direction of rotation. The time-rate of change of angular frequency is the scalar version of angular acceleration (rad/s²). This change is caused by the scalar version of the torque, which can have a positive or negative value in accordance with the conven ...

See also:

Rotation around a fixed axis, Rotation around a fixed axis - Speed of rotation angular acceleration and torque, Rotation around a fixed axis - Vectors, Rotation around a fixed axis - Centripetal force, Rotation around a fixed axis - Constant angular speed

Read more here: » Rotation around a fixed axis: Encyclopedia II - Rotation around a fixed axis - Speed of rotation angular acceleration and torque

Quantum mechanics is a physical science dealing with the behaviour of matter and electromagnetic waves on the scale of atoms and subatomic particles. Since all matter is made of atoms, quantum mechanics is also important in understanding how large objects such as stars and galaxies and even the Big Bang can be analyzed and explained. Quantum mechanical departures from classical physics are most often encountered at small length scales, very low or very high energies, or extremely low temperatures. Quantum mechanics is the basis of mod ...

Including:

• Basics of quantum mechanics - Background
• Basics of quantum mechanics - Old quantum theory
• Basics of quantum mechanics - Planck's constant
• Basics of quantum mechanics - Reduced Planck's constant
• Basics of quantum mechanics - Bohr atom
• Basics of quantum mechanics - Wave-particle duality
• Basics of quantum mechanics - Development of modern quantum mechanics
• Basics of quantum mechanics - Full quantum mechanical theory
• Basics of quantum mechanics - Schrödinger wave equation
• Basics of quantum mechanics - Uncertainty Principle
• Basics of quantum mechanics - Wavefunction collapse
• Basics of quantum mechanics - Eigenstates and eigenvalues
• Basics of quantum mechanics - The Pauli Exclusion Principle
• Basics of quantum mechanics - Dirac wave equation
• Basics of quantum mechanics - Quantum entanglement
• Basics of quantum mechanics - Notes

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A binary star system consists of two stars both orbiting around their barycenter. For each star, the other is its "companion star". The term "binary star" was apparently first coined by Sir William Herschel in 1802 to designate "a real double star — the union of two stars that are formed together in one system by the laws of attraction". Any two stars seen close to one another form a double star, the most famous being Mizar and Alcor in the Big Dipper. Odds are, though, that a double star is probably a foreground and b ...

Including:

• Binary star - Binary star classifications
• Binary star - Research findings
• Binary star - Binary star examples

Read more here: » Binary star: Encyclopedia - Binary star

The center of mass of an object is a point at which the object's mass can be assumed, for many purposes, to be concentrated. Center of mass - Example. For example, an object can balance on a point only if its center of mass is directly above the point. Alternatively, if you hang an object from a string, the object's center of mass will be directly below the string. Center of gravity, Centroid, Pappus's centroid theorem, Center of pressure Center ...

Including:

• Center of mass - Example
• Center of mass - Comparison with center of gravity
• Center of mass - Definition
• Center of mass - More formulas
• Center of mass - Aeronautical significance
• Center of mass - Motion of the center of mass
• Center of mass - Examples
• Center of mass - Barycenter
• Center of mass - Animations

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The orbital speed of a body, generally a planet, a natural satellite, an artificial satellite, or a multiple star, is the speed at which it orbits around the barycenter of a system, usually around a more massive body. It can be used to refer to either the mean orbital speed, the average speed as it completes an orbit, or instantaneous orbital speed, the speed at a particular point in its orbit. The orbital speed at any position in the orbit can be computed from the distance to the central body at that position, and the specific orbital energy, which is independent of position: the kinetic en ...

Including:

• Orbital speed - Radial trajectories
• Orbital speed - Transverse orbital speed
• Orbital speed - Mean orbital speed

Read more here: » Orbital speed: Encyclopedia - Orbital speed

Symmetry is a characteristic of geometrical shapes, equations, and other objects; we say that such an object is symmetric with respect to a given operation if this operation, when applied to the object, does not appear to change it. Two objects are symmetric to each other with respect to a given group of operations if one is obtained from the other by one of the operations. In 2D geometry the main kinds of symmetry of interest are with respect to the basic Euclidean plane isometries: translations, rotations, reflections, ...

Including:

• Symmetry - Mathematical model for symmetry
• Symmetry - Non-isometric symmetry
• Symmetry - Reflection symmetry
• Symmetry - Rotational symmetry
• Symmetry - Translational symmetry
• Symmetry - Glide reflection symmetry
• Symmetry - Rotoreflection symmetry
• Symmetry - Screw axis symmetry
• Symmetry - Symmetry combinations
• Symmetry - Color
• Symmetry - Similarity vs. sameness
• Symmetry - More on symmetry in geometry
• Symmetry - Symmetry in mathematics
• Symmetry - Symmetry in logic
• Symmetry - Generalization of symmetry
• Symmetry - Symmetry in physics
• Symmetry - Symmetry in biology
• Symmetry - Symmetry in chemistry
• Symmetry - Symmetry in the arts and crafts
• Symmetry - Architecture
• Symmetry - Pottery
• Symmetry - Quilts
• Symmetry - Carpets rugs
• Symmetry - Music
• Symmetry - Other arts and crafts
• Symmetry - Aesthetics
• Symmetry - Symmetry in games and puzzles
• Symmetry - Symmetry in literature
• Symmetry - Symmetry in telecommunications
• Symmetry - Moral symmetry
• Symmetry - Related topics

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edit A black hole is a concentration of mass great enough that the force of gravity prevents anything from escaping it except through quantum tunnelling behaviour (known as Hawking Radiation). The gravitational field is so strong that the escape velocity near it exceeds the speed of light. This implies that nothing, not even light, can escape its gravity, hence the word "black". The term "black hole" is widespread, even though it does not refer to a hole in the usual sense, but rather a region of space fro ...

Including:

• Black hole - History
• Black hole - Evidence
• Black hole - Formation
• Black hole - Observation
• Black hole - Have we found them?
• Black hole - Recent discoveries
• Black hole - Features and issues
• Black hole - The event horizon
• Black hole - The singularity
• Black hole - Entering a black hole
• Black hole - Rotating black holes
• Black hole - Entropy and Hawking radiation
• Black hole - Black hole unitarity
• Black hole - Mathematical theory
• Black hole - Alternative models

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The Azimuthal quantum number (or orbital angular momentum quantum number) symbolized as l is a quantum number for an atomic orbital which determines its orbital angular momentum. The azimuthal quantum number is the second of a set of quantum numbers which describe the unique quantum state of an electron and is designated by the letter l. Azimuthal quantum number - Derivation. There are a set of quantum numbers associated with the energy states of the atom. The four quantum numbers n< ...

Including:

• Azimuthal quantum number - Derivation
• Azimuthal quantum number - History

Read more here: » Azimuthal quantum number: Encyclopedia - Azimuthal quantum number

In physics a special field has been created entirely centered around the thermodynamics of black holes. Within black holes many of the physical laws which we accept should break down, including those of thermodynamics. Black hole thermodynamics - Problem one. Classical thermodynamics states as its second principle that entropy is an always increasing function in a closed system - and the universe is a closed system, as nothing can escape it. So we ask; what happens to the information when a particle ...

Including:

• Black hole thermodynamics - Problem one
• Black hole thermodynamics - Problem two

Read more here: » Black hole thermodynamics: Encyclopedia - Black hole thermodynamics

The accretion theory, in astrophysics, is a scientific theory of the formation of our Solar system. The theory maintains that there existed a large, dense cloud of interstellar gas (the solar nebula), which began contracting under the pressure of its own gravity. In order to conserve its angular momentum, the nebula also began rotating, turning into an accretion disc, with a lump of matter accumulating at the center (the protosun). This lump eventually reached the conditions of temperature and pressure neede ...

Read more here: » Accretion theory: Encyclopedia - Accretion theory

In mathematics, the cross product is a binary operation on vectors in a three-dimensional Euclidean space. It is also known as the vector product or outer product. It differs from the dot product in that it results in a vector rather than in a scalar. Its main use lies in the fact that the cross product of two vectors is orthogonal to both of them. Cross product - Definition. The cross product of the two vectors a and b is denoted by a × b (in longhand some mathema ...

Including:

• Cross product - Definition
• Cross product - Properties
• Cross product - Geometric meaning
• Cross product - Algebraic properties
• Cross product - Associativity
• Cross product - Matrix notation
• Cross product - Lagrange's formula
• Cross product - Applications
• Cross product - Higher dimensions
• Cross product - Symbol

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Countersteering is the name given to the "counter-intuitive" technique used by cyclists to turn corners. Countersteering - A Technical Description. The spinning front wheel of a bicycle or a motorcycle responds to steering inputs exactly like the spinning flywheel of a gyroscope. Both the high-speed and the low-speed steering response are described by the laws of physics, namely the conservation of angular momentum. A detailed description and proof for both speed regimes will be included in this section.

• Countersteering - A Technical Description
• Countersteering - An Intuitive Approach
• Countersteering - The throw it off balance method

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In atomic physics, the Bohr model depicts the atom as a small, positively charged nucleus surrounded by electrons in orbit - similar in structure to the solar system, but with electrostatic forces providing attraction, rather than gravity. Its key success was in explaining the Rydberg formula for the spectral emission lines of atomic hydrogen; while the Rydberg formula had been known experimentally, it did not gain a theoretical underpinning until the Bohr model was introduced. The Bohr model is not a complete model of the atom, and f ...

Including:

• Bohr model - History
• Bohr model - Refinements
• Bohr model - Electron energy levels in hydrogen
• Bohr model - Energy in terms of other constants
• Bohr model - Rydberg Formula
• Bohr model - Shortcomings

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In mathematics and physics, continuous spectrum is, roughly speaking, a non-countable set of eigenvalues of an operator. An operator acting on a Hilbert space is said to have a continuous spectrum if its eigenvalues can be changed continuously. If the spectrum of an operator is not continuous, we say that it is has discrete spectrum. Some of the basic questions in spectral theory are to characterise the discrete spectrum and purely continuous spectrum, just as a measure, such as a probability measure, can typically ...

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Gravity is a force of attraction that acts between bodies that have mass. It is a physical phenomenon of fundamental importance, profoundly affecting the workings of the world around us and the universe beyond. Most familiarly, it is the gravitational attraction of the earth that endows objects with weight and causes them to fall to the ground when dropped. In fact, gravity is also the reason for the very existence of the earth, the sun and other celestial bodies; without it matter would not have coalesced into these bodies and ...

Including:

• Gravity - Overview of the history of gravitational theory
• Gravity - Newton's law of universal gravitation
• Gravity - Acceleration due to gravity
• Gravity - Bodies with spatial extent
• Gravity - Vector form
• Gravity - Gravitational field
• Gravity - The Earth's gravity
• Gravity - Comparative gravities of the Earth Sun Moon and planets
• Gravity - Mathematical equations for a falling body
• Gravity - Gravitational potential
• Gravity - Acceleration relative to the rotating Earth
• Gravity - Gravity and astronomy
• Gravity - Self-gravitating system
• Gravity - Practical uses of gravity
• Gravity - Problems with Newton's theory
• Gravity - Theoretical concerns
• Gravity - Disagreement with observation
• Gravity - Newton's reservations
• Gravity - Einstein's theory of gravitation
• Gravity - Experimental tests
• Gravity - Comparison with electromagnetic force
• Gravity - Gravity and quantum mechanics
• Gravity - Alternative theories
• Gravity - Recent alternative theories
• Gravity - Historical alternative theories
• Gravity - Notes

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L is the twelfth letter of the Latin alphabet. Its name in English is el. L - History. The letter L is derived ultimately from the Semitic (crook/goad) which stood for the phonetic value /l/ as did the Greek letter Lambda Λ (upper case) or λ (lower case), as well as the equivalent Etruscan and Latin letters. In reference, it is spelled el or ell. L - Usage. In English, L can have several values, depending on whether it occurs before or ...

Including:

• L - History
• L - Usage
• L - Alternative representations
• L - Computing
• L - Things named L
• L - Things abbreviated as L
• L - Alternate meanings for the symbol L

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In meteorology, a tropical cyclone (also referred to as a tropical depression, tropical storm, typhoon, or hurricane depending on strength and geographical context) is a type of low pressure system which generally forms in the tropics. While they can be highly destructive, tropical cyclones are an important part of the atmospheric circulation system, which moves heat from the equatorial region toward the higher latitudes. Tropical cyclone - Terms for tropical cyclones. Depending on the regi ...

Including:

• Tropical cyclone - Terms for tropical cyclones
• Tropical cyclone - Etymology
• Tropical cyclone - Overall mechanics of a tropical cyclone
• Tropical cyclone - Formation
• Tropical cyclone - Times of formation
• Tropical cyclone - Locations of formation
• Tropical cyclone - Structure and classification
• Tropical cyclone - Intensities of tropical cyclones
• Tropical cyclone - Categories and ranking
• Tropical cyclone - Other storm systems
• Tropical cyclone - Movement and track
• Tropical cyclone - Large-scale winds
• Tropical cyclone - Coriolis effect
• Tropical cyclone - Interaction with high and low pressure systems
• Tropical cyclone - Forecasting
• Tropical cyclone - Landfall
• Tropical cyclone - Dissipation
• Tropical cyclone - Artificial dissipation
• Tropical cyclone - Monitoring observation and tracking
• Tropical cyclone - Naming of tropical cyclones
• Tropical cyclone - Renaming of tropical cyclones
• Tropical cyclone - Effects
• Tropical cyclone - Beneficial effects of tropical cyclones
• Tropical cyclone - Long term trends in cyclone activity
• Tropical cyclone - Global warming?
• Tropical cyclone - Notable cyclones

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The cat, also called the domestic cat or house cat, is a small feline carnivorous mammal of the subspecies Felis silvestris catus. Its most immediate, pre-domestication ancestor is the African wild cat, Felis silvestris lybica. The cat has been living in close association with humans for at least 3,500 years; the Ancient Egyptians routinely used cats to keep mice and other rodents away from their grain (and also believed that cats were sacred). The history of the domestic cat may stretch back even further, ...

Including:

• Cat - Characteristics
• Cat - Physical
• Cat - Senses
• Cat - Communication
• Cat - Hunting and diet
• Cat - Hygiene
• Cat - Environment
• Cat - Reproduction and genetics
• Cat - Domestication
• Cat - Feral cats
• Cat - Environmental issues
• Cat - Scientific classification
• Cat - Varieties of domestic cat
• Cat - History and mythology

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A bicycle, or bike, is a pedal-driven land vehicle with two wheels attached to a frame, one behind the other. First introduced in 19th-century Europe, bicycles evolved quickly into their familiar, current design. Numbering over 1,000,000,000 in the world today, bicycles provide the principal means of transportation in many regions and a popular form of recreational transport in others. To distinguish a bicycle from a mot ...

Including:

• Bicycle - History
• Bicycle - Technical aspects
• Bicycle - Legal requirements
• Bicycle - Construction and parts
• Bicycle - Performance
• Bicycle - Bicycle physics
• Bicycle - Social and historical aspects
• Bicycle - Economic and social implications
• Bicycle - Bicycles at work
• Bicycle - Bicycle recreation
• Bicycle - Bicycles and war
• Bicycle - Bicycle racing
• Bicycle - Modal share: cycle use in modern cities
• Bicycle - Cycling activism
• Bicycle - Types of bicycle
• Bicycle - Standards
• Bicycle - Notes

Read more here: » Bicycle: Encyclopedia - Bicycle

In mechanics, the two-body problem is a special case of the n-body problem that admits a closed form solution. The most commonly encountered version of the problem, involving an inverse square law force, is encountered in celestial mechanics and the Bohr model of the hydrogen atom. This problem was first solved by Isaac Newton. This article deals with the general case where it is not assumed that one body has a much smaller mass than the other one. Two-body problem - Statement of problem. ...

Including:

• Two-body problem - Statement of problem
• Two-body problem - Sketch of solution
• Two-body problem - Reduction to a single body problem
• Two-body problem - Reduction to two dimensions
• Two-body problem - Change of variables
• Two-body problem - Newtonian Gravity
• Two-body problem - General Relativistic Gravity
• Two-body problem - Examples
• Two-body problem - Other uses

Read more here: » Two-body problem: Encyclopedia - Two-body problem