power

power, in physics

power, in physics, time rate of doing work or of producing or expending energy. The unit of power based on the English units of measurement is the horsepower, devised for describing mechanical power by James Watt, who estimated that a horse can do 550 ft-lb of work per sec; a foot-pound is the work done when a weight (force) of 1 lb is moved through a distance of 1 ft. The unit of power in the metric system is the watt, named in honor of James Watt and equal to 1 joule per sec; the watt is used for measuring electric power in most countries, even those still using English units for other quantities. In common usage, the terms power and energy have become synonymous; for example, electrical energy is usually referred to as electric power (see power, electric). See also energy, sources of.

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power, in mathematics

power, in mathematics: see exponent.

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power

In science and engineering, the time rate of doing work or delivering energy. Power (P) can be expressed as the amount of work done (W), or energy transferred, divided by the time interval (t): P = W/t. A given amount of work can be done by a low-powered motor in a long time or by a high-powered motor in a short time. Units of power are those of work (or energy) per unit time, such as foot-pounds per minute, joules per second (called watts), or ergs per second. Power can also be expressed as the product of the force (F) applied to move an object and the speed (v) of the object in the direction of the force: P = Fv. See also horsepower.

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power

(1) See computer power.

(2) (POWER) (Performance Optimization With Enhanced RISC) A RISC-based CPU architecture from IBM used in its pSeries, iSeries and i5 computer lines. The PowerPC, enhanced by Motorola and Apple, is a single-chip version of the POWER architecture. POWER CPUs and PowerPC CPUs share a common instruction set that provides binary compatibility in some cases or compatibility by recompilation. Following is the evolution of POWER chips. See PowerPC, iSeries and pSeries.

                    Word
  POWER     Year    Size   # of
  Series    Intro. (bits)  Trans.  Features

  POWER5    2004     64   276M
  POWER4+   2002     64   180M     0.13 process
  POWER4    2001     64   174M
  POWER3-II 2000     64   15M      copper
  POWER3    1998     64   15M      SMP

  POWER2    1993     32   15M
  POWER1    1990     32   800K

  SMP = See symmetric multiprocessing.
  copper = See copper chip.
  0.13 process = See process technology.

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power

1. control or dominion or a position of control, dominion, or authority

2. a state or other political entity with political, industrial, or military strength

3. 

a. legal authority to act, esp in a specified capacity, for another

b. the document conferring such authority

4. Maths

a. the value of a number or quantity raised to some exponent

b. another name for exponent

5. Physics Engineering a measure of the rate of doing work expressed as the work done per unit time. It is measured in watts, horsepower, etc.

6. 

a. the rate at which electrical energy is fed into or taken from a device or system. It is expressed, in a direct-current circuit, as the product of current and voltage and, in an alternating-current circuit, as the product of the effective values of the current and voltage and the cosine of the phase angle between them. It is measured in watts

b. (as modifier): a power amplifier

7. 

a. mechanical energy as opposed to manual labour

b. (as modifier): a power mower

8. 

a. a measure of the ability of a lens or optical system to magnify an object, equal to the reciprocal of the focal length. It is measured in dioptres

b. another word for magnification

9. the sixth of the nine orders into which the angels are traditionally divided in medieval angelology

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power [′pau̇·ər]

(mathematics)

The value that is assigned to a mathematical expression and its exponent.

The power of a set is its cardinality.

For a point, with reference to a circle, the quantity (x-a)²+ (y-b)²-r², wherexandyare the coordinates of the point,aandbare the coordinates of the center of the circle, andris the radius of the circle.

For a point, with reference to a sphere, the quantity (x-a)²+ (y-b)²+ (z-c)²-r², wherex,y, andzare the coordinates of the point;a,b, andcare the coordinates of the center of the sphere; andris the radius of the sphere.

(optics)

focal power

(physics)

The time rate of doing work.

(statistics)

One minus the probability that a given test causes the acceptance of the null hypothesis when it is false due to the validity of an alternative hypothesis; this is the same as the probability of rejecting the null hypothesis by the test when the alternative is true.

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Power

The time rate of doing work. Like work, power is a scalar quantity, that is, a quantity which has magnitude but no direction. Some units often used for the measurement of power are the watt (1 joule of work per second) and the horsepower (550 foot-pounds of work per second). See Work

Power is a concept which can be used to describe the operation of any system or device in which a flow of energy occurs. In many problems of apparatus design, the power, rather than the total work to be done, determines the size of the component used. Any device can do a large amount of work by performing for a long time at a low rate of power, that is, by doing work slowly. However, if a large amount of work must be done rapidly, a high-power device is needed. High-power machines are usually larger, more complicated, and more expensive than equipment which need operate only at low power. A motor which must lift a certain weight will have to be larger and more powerful if it lifts the weight rapidly than if it raises it slowly. An electrical resistor must be large in size if it is to convert electrical energy into heat at a high rate without being damaged.

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Power

Force, The

mystical source of a Jedi Knight’s righteous power. [Am. Cinema: Star Wars and sequels]

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POWER - Performance Optimization with Enhanced RISC. The IBM processor architecture on which PowerPC was based.