HOME  TheInfoList.com 
SI Derived Unit The International System of Units International System of Units (SI) specifies a set of seven base units from which all other SI units of measurement are derived. These SI DERIVED UNITS are either dimensionless , or can be expressed as a product of one or more of the base units, possibly scaled by an appropriate power of exponentiation . Many derived units do not have special names. For example, the SI derived unit of area is the square metre (m2) and the SI derived unit of density is the kilogram per cubic metre (kg/m3 or kg m−3). However, 22 derived units are recognized by the SI with special names, which are written in lowercase. However, the symbols for units named after persons, are always written with an uppercase initial letter. For example, the symbol for the hertz is "Hz"; but the symbol for the metre is "m" [...More...]  "SI Derived Unit" on: Wikipedia Yahoo 

Quantity Of Electricity CONTENTS* 1 Historical drift * 1.1 PreEnglish origins * 1.2 Entry into English * 2 Conceptual problems * 3 References * 4 External links HISTORICAL DRIFTPREENGLISH ORIGINSThe New Latin adjective electricus, originally meaning 'of amber ', was first used to refer to amber's attractive properties by William Gilbert in his 1600 text De Magnete . The term came from the classical Latin electrum, amber, from the Greek ἤλεκτρον (elektron), amber. The origin of the Greek word is unknown, but there is speculation that it might have come from a Phoenician word elēkrŏn, meaning 'shining light'. The letter Q was used for electric charge instead of the letter E because the letter was already used to represent the electron. ENTRY INTO ENGLISHThe word electric was first used by Francis Bacon Francis Bacon to describe materials like amber that attracted other objects [...More...]  "Quantity Of Electricity" on: Wikipedia Yahoo 

Force any interaction that, when unopposed, will change the motion of an object For other uses, see Force (other) . FORCE Forces are also described as a push or pull on an object. They can be due to phenomena such as gravity , magnetism , or anything that might cause a mass to accelerate [...More...]  "Force" on: Wikipedia Yahoo 

Solid Angle In geometry , a SOLID ANGLE (symbol: Ω) is the twodimensional angle in threedimensional space that an object subtends at a point. It is a measure of how large the object appears to an observer looking from that point. In the International System of Units International System of Units (SI), a solid angle is expressed in a dimensionless unit called a steradian (symbol: sr). A small object nearby may subtend the same solid angle as a larger object farther away. For example, although the Moon Moon is much smaller than the Sun Sun , it is also much closer to Earth Earth . Indeed, as viewed from any point on Earth, both objects have approximately the same solid angle as well as apparent size. This is evident during a solar eclipse [...More...]  "Solid Angle" on: Wikipedia Yahoo 

Angle 2D ANGLES * Right * Interior * Exterior 2D ANGLE PAIRS * Adjacent * Vertical * Complementary * Supplementary * Transversal 3D ANGLES * Dihedral An angle formed by two rays emanating from a vertex. ∠, the angle symbol in Unicode Unicode is U+2220 . In planar geometry , an ANGLE is the figure formed by two rays , called the sides of the angle, sharing a common endpoint, called the vertex of the angle. Angles formed by two rays lie in a plane, but this plane does not have to be a Euclidean plane . Angles are also formed by the intersection of two planes in Euclidean and other spaces . These are called dihedral angles . Angles formed by the intersection of two curves in a plane are defined as the angle determined by the tangent rays at the point of intersection [...More...]  "Angle" on: Wikipedia Yahoo 

Physical Quantity A PHYSICAL QUANTITY is a physical property of a phenomenon , body, or substance, that can be quantified by measurement . A physical quantity can be expressed as the combination of a magnitude expressed by a number – usually a real number – and a unit ; for example, 6973167492749999999♠1.6749275×10−27 kg (the mass of the neutron ), or 7008299792458000000♠299792458 metres per second (the speed of light ). Physical quantities are measured as n u {textstyle nu} where n {textstyle n} is the magnitude and u {textstyle u} is the unit. For example: A person has measured the length of a room as 3 m. Here 3 is magnitude and m (metre) is the unit. 3 m can also be written as 300 cm. The same physical quantity x {textstyle x} can be represented equivalently in many unit systems, i.e. x = n 1 u 1 = n 2 u 2 {textstyle x=n_{1}u_{1}=n_{2}u_{2}} [...More...]  "Physical Quantity" on: Wikipedia Yahoo 

Weight the force on an object due to gravity This page is about the physical concept. In law, commerce, and in colloquial usage weight may also refer to mass . For other uses see weight (other) . WEIGHT A spring scale measures the weight of an object. COMMON SYMBOLS W {displaystyle W} SI UNIT newton (N) OTHER UNITS poundforce (lbf) IN SI BASE UNITS kg⋅m⋅s−2 EXTENSIVE ? Yes INTENSIVE ? No CONSERVED ? No Derivations from other quantities * W = m g {displaystyle W=mg} * W = m a {displaystyle W=ma} DIMENSION M L T 2 {displaystyle {mathsf {MLT}}^{2}} In science and engineering , the WEIGHT of an object is usually taken to be the force on the object due to gravity [...More...]  "Weight" on: Wikipedia Yahoo 

Electric Charge ELECTRIC CHARGE is the physical property of matter that causes it to experience a force when placed in an electromagnetic field . There are two types of electric charges: positive and negative (commonly carried by protons and electrons respectively). Like charges repel and unlike attract. An absence of net charge is referred to as neutral. An object is negatively charged if it has an excess of electrons , and is otherwise positively charged or uncharged. The SI derived unit of electric charge is the coulomb (C). In electrical engineering , it is also common to use the amperehour (Ah), and, in chemistry , it is common to use the elementary charge (e) as a unit. The symbol Q often denotes charge. Early knowledge of how charged substances interact is now called classical electrodynamics , and is still accurate for problems that don't require consideration of quantum effects [...More...]  "Electric Charge" on: Wikipedia Yahoo 

Power (physics) In physics, POWER is the rate of doing work . It is the amount of energy consumed per unit time. Having no direction, it is a scalar quantity. In the SI system , the unit of power is the joule per second (J/s), known as the watt in honour of James Watt Watt , the eighteenthcentury developer of the steam engine . Another common and traditional measure is horsepower (comparing to the power of a horse). Being the rate of work, the equation for power can be written: P = W t {displaystyle P={frac {W}{t}}} The integral of power over time defines the work performed. Because this integral depends on the trajectory of the point of application of the force and torque, this calculation of work is said to be path dependent . As a physical concept, power requires both a change in the physical universe and a specified time in which the change occurs [...More...]  "Power (physics)" on: Wikipedia Yahoo 

Mechanical Work W = F ⋅ S W = τ θ CLASSICAL MECHANICS F = m a {displaystyle {vec {F}}=m{vec {a}}} Second law of motion * History * Timeline Branches * Applied * Celestial * Continuum * Dynamics * Kinematics Kinematics * Kinetics * Statics * Statistical Fundamentals * [...More...]  "Mechanical Work" on: Wikipedia Yahoo 

Radiant Flux In radiometry , RADIANT FLUX or RADIANT POWER is the radiant energy emitted, reflected, transmitted or received, per unit time, and SPECTRAL FLUX or SPECTRAL POWER is the radiant flux per unit frequency or wavelength , depending on whether the spectrum is taken as a function of frequency or of wavelength. The SI unit of radiant flux is the watt (W), that is the joule per second (J/s) in SI base units, while that of spectral flux in frequency is the watt per hertz (W/Hz) and that of spectral flux in wavelength is the watt per metre (W/m)—commonly the watt per nanometre (W/nm) [...More...]  "Radiant Flux" on: Wikipedia Yahoo 

Stress (physics) In continuum mechanics , STRESS is a physical quantity that expresses the internal forces that neighboring particles of a continuous material exert on each other, while strain is the measure of the deformation of the material. For example, when a solid vertical bar is supporting a weight , each particle in the bar pushes on the particles immediately below it. When a liquid is in a closed container under pressure , each particle gets pushed against by all the surrounding particles. The container walls and the pressure inducing surface (such as a piston) push against them in (Newtonian) reaction . These macroscopic forces are actually the net result of a very large number of intermolecular forces and collisions between the particles in those molecules . Strain inside a material may arise by various mechanisms, such as stress as applied by external forces to the bulk material (like gravity ) or to its surface (like contact forces , external pressure, or friction ) [...More...]  "Stress (physics)" on: Wikipedia Yahoo 

Pressure PRESSURE (symbol: p or P) is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled gage pressure) is the pressure relative to the ambient pressure. Various units are used to express pressure. Some of these derive from a unit of force divided by a unit of area; the SI unit SI unit of pressure, the pascal (Pa), for example, is one newton per square metre ; similarly, the poundforce per square inch (psi ) is the traditional unit of pressure in the imperial and US customary systems. Pressure may also be expressed in terms of standard atmospheric pressure ; the atmosphere (atm) is equal to this pressure, and the torr is defined as 1⁄760 of this. Manometric units such as the centimetre of water , millimetre of mercury , and inch of mercury are used to express pressures in terms of the height of column of a particular fluid in a manometer [...More...]  "Pressure" on: Wikipedia Yahoo 

Heat In thermodynamics , HEAT refers to the energy that is transferred from a warmer substance or body to a cooler one. More generally, heat arises from many microscopicscale changes to the objects, and can be defined as the amount of transferred energy excluding both macroscopic work and transfer of part of the object itself. Transfer of energy as heat can occur through contact, or through a common wall that is impermeable to matter, between the source and the destination body, as in conduction ; or by radiation between remote bodies; or by way of an intermediate fluid body, as in convective circulation ; or by a combination of these. Heat Heat is often contrasted with work : heat involves the stochastic (random) motion of particles (such as atoms or molecules) that are equally distributed among all degrees of freedom , while work is directional, confined to one or more specific degrees of freedom [...More...]  "Heat" on: Wikipedia Yahoo 

Symbol A SYMBOL is a mark, sign, or word that indicates, signifies, or is understood as representing an idea, object, or relationship. Symbols allow people to go beyond what is known or seen by creating linkages between otherwise very different concepts and experiences. All communication (and data processing) is achieved through the use of symbols. Symbols take the form of words, sounds, gestures, ideas or visual images and are used to convey other ideas and beliefs. For example, a red octagon may be a symbol for "STOP". On a map, a blue line might represent a river. Numerals are symbols for numbers . Alphabetic letters may be symbols for sounds. Personal names are symbols representing individuals. A red rose may symbolize love and compassion. The variable 'x', in a mathematical equation, may symbolize the position of a particle in space. In cartography , an organized collection of symbols forms a legend for a map [...More...]  "Symbol" on: Wikipedia Yahoo 

Power (mathematics) EXPONENTIATION is a mathematical operation , written as BN, involving two numbers, the BASE b and the EXPONENT n. When n is a positive integer , exponentiation corresponds to repeated multiplication of the base: that is, bn is the product of multiplying n bases: b n = b b n {displaystyle b^{n}=underbrace {btimes cdots times b} _{n}} The exponent is usually shown as a superscript to the right of the base. In that case, bn is called b raised to the nth power, b raised to the power of n, or the nth power of b. When n is a positive integer and b is not zero, b−n is naturally defined as 1/bn, preserving the property bn × bm = bn + m. With exponent −1, b−1 is equal to 1/b, and is the reciprocal of b. The definition of exponentiation can be extended to allow any real or complex exponent. Exponentiation Exponentiation by integer exponents can also be defined for a wide variety of algebraic structures, including matrices [...More...]  "Power (mathematics)" on: Wikipedia Yahoo 