Misplaced Pages

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46-416: By day, KGNW is powered at 50,000 watts , the maximum for commercial stations. But 820 AM is a clear channel frequency reserved for Class A WBAP Fort Worth . So to avoid interference, at night KGNW reduces power to 5,000 watts. It uses a directional antenna with a three- tower array at all times. The transmitter is off 105th Street SW on Vashon Island . The station is licensed to broadcast in

92-518: A PBS - affiliated television station owned by Iowa Public Television in Davenport, Iowa . The 1150 AM station in Seattle was sold to Hubbard Broadcasting and is now talk radio outlet KKNW . 47°26′00″N 122°28′02″W  /  47.43333°N 122.46722°W  / 47.43333; -122.46722 Watt The watt (symbol: W ) is the unit of power or radiant flux in

138-558: A light bulb with a power rating of 100 W is turned on for one hour, the energy used is 100 watt hours (W·h), 0.1 kilowatt hour, or 360  kJ . This same amount of energy would light a 40-watt bulb for 2.5 hours, or a 50-watt bulb for 2 hours. Power stations are rated using units of power, typically megawatts or gigawatts (for example, the Three Gorges Dam in China is rated at approximately 22 gigawatts). This reflects

184-513: A motor is the product of the torque that the motor generates and the angular velocity of its output shaft. Likewise, the power dissipated in an electrical element of a circuit is the product of the current flowing through the element and of the voltage across the element. Power is the rate with respect to time at which work is done; it is the time derivative of work : P = d W d t , {\displaystyle P={\frac {dW}{dt}},} where P

230-399: A force F A acting on a point that moves with velocity v A and the output power be a force F B acts on a point that moves with velocity v B . If there are no losses in the system, then P = F B v B = F A v A , {\displaystyle P=F_{\text{B}}v_{\text{B}}=F_{\text{A}}v_{\text{A}},} and

276-485: A logarithmic measure relative to a reference of 1 milliwatt, calories per hour, BTU per hour (BTU/h), and tons of refrigeration . As a simple example, burning one kilogram of coal releases more energy than detonating a kilogram of TNT , but because the TNT reaction releases energy more quickly, it delivers more power than the coal. If Δ W is the amount of work performed during a period of time of duration Δ t ,

322-452: A period of one year: equivalent to approximately 114 megawatts of constant power output. The watt-second is a unit of energy, equal to the joule . One kilowatt hour is 3,600,000 watt seconds. While a watt per hour is a unit of rate of change of power with time, it is not correct to refer to a watt (or watt-hour) as a watt per hour. Power (physics) Power is the amount of energy transferred or converted per unit time. In

368-420: A periodic function of period T {\displaystyle T} . The peak power is simply defined by: P 0 = max [ p ( t ) ] . {\displaystyle P_{0}=\max[p(t)].} The peak power is not always readily measurable, however, and the measurement of the average power P a v g {\displaystyle P_{\mathrm {avg} }}

414-541: A turbine, which generates 648 MW e (i.e. electricity). Other SI prefixes are sometimes used, for example gigawatt electrical (GW e ). The International Bureau of Weights and Measures , which maintains the SI-standard, states that further information about a quantity should not be attached to the unit symbol but instead to the quantity symbol (e.g., P th = 270 W rather than P = 270 W th ) and so these unit symbols are non-SI. In compliance with SI,

460-495: A unit of time, namely 1 J/s. In this new definition, 1 absolute watt = 1.00019 international watts. Texts written before 1948 are likely to be using the international watt, which implies caution when comparing numerical values from this period with the post-1948 watt. In 1960, the 11th General Conference on Weights and Measures adopted the absolute watt into the International System of Units (SI) as

506-452: Is a Class A station powered at 50,000 watts. KQIN moved to the 820 AM dial position on January 1, 1987. The KGNW call letters and its Christian talk and teaching format were removed from 1150 AM and relocated to 820 AM. The move allowed KGNW to increase its daytime power to 50,000 watts and add nighttime power at 5,000 watts, using a directional antenna. Today, the KQIN call sign belongs to

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552-412: Is constant, the amount of work performed in time period t can be calculated as W = P t . {\displaystyle W=Pt.} In the context of energy conversion, it is more customary to use the symbol E rather than W . Power in mechanical systems is the combination of forces and movement. In particular, power is the product of a force on an object and the object's velocity, or

598-452: Is given by P ( t ) = p Q , {\displaystyle P(t)=pQ,} where p is pressure in pascals or N/m , and Q is volumetric flow rate in m /s in SI units. If a mechanical system has no losses, then the input power must equal the output power. This provides a simple formula for the mechanical advantage of the system. Let the input power to a device be

644-543: Is held constant at one meter per second against a constant opposing force of one newton , the rate at which work is done is one watt. 1   W = 1   J / s = 1   N ⋅ m / s = 1   k g ⋅ m 2 ⋅ s − 3 . {\displaystyle \mathrm {1~W=1~J{/}s=1~N{\cdot }m{/}s=1~kg{\cdot }m^{2}{\cdot }s^{-3}} .} In terms of electromagnetism , one watt

690-675: Is more commonly performed by an instrument. If one defines the energy per pulse as ε p u l s e = ∫ 0 T p ( t ) d t {\displaystyle \varepsilon _{\mathrm {pulse} }=\int _{0}^{T}p(t)\,dt} then the average power is P a v g = 1 T ∫ 0 T p ( t ) d t = ε p u l s e T . {\displaystyle P_{\mathrm {avg} }={\frac {1}{T}}\int _{0}^{T}p(t)\,dt={\frac {\varepsilon _{\mathrm {pulse} }}{T}}.} One may define

736-733: Is named after the Scottish inventor James Watt . The unit name was proposed by C. William Siemens in August 1882 in his President's Address to the Fifty-Second Congress of the British Association for the Advancement of Science . Noting that units in the practical system of units were named after leading physicists, Siemens proposed that watt might be an appropriate name for a unit of power. Siemens defined

782-414: Is power, W is work, and t is time. We will now show that the mechanical power generated by a force F on a body moving at the velocity v can be expressed as the product: P = d W d t = F ⋅ v {\displaystyle P={\frac {dW}{dt}}=\mathbf {F} \cdot \mathbf {v} } If a constant force F is applied throughout a distance x ,

828-524: Is supplied by SRN News . The station signed on the air on October 10, 1970 ; 54 years ago  ( 1970-10-10 ) . Its original call sign was KQIN and it broadcast on 800 kHz. The station was a daytimer , required to go off the air at sunset. It was owned and operated by John Mowbray who also served as general manager. KQIN played country music and competed with 1150 KAYO (now KKNW ), 101.5 KETO (now KPLZ ) and later KMPS-FM 94.1 (now KSWD ). As more country music listeners switched to

874-401: Is the electrical resistance , measured in ohms . In the case of a periodic signal s ( t ) {\displaystyle s(t)} of period T {\displaystyle T} , like a train of identical pulses, the instantaneous power p ( t ) = | s ( t ) | 2 {\textstyle p(t)=|s(t)|^{2}} is also

920-499: Is the limiting value of the average power as the time interval Δ t approaches zero. P = lim Δ t → 0 P a v g = lim Δ t → 0 Δ W Δ t = d W d t . {\displaystyle P=\lim _{\Delta t\to 0}P_{\mathrm {avg} }=\lim _{\Delta t\to 0}{\frac {\Delta W}{\Delta t}}={\frac {dW}{dt}}.} When power P

966-701: Is the nation's largest owner of Christian radio stations and gave the 1150 station a Christian talk and teaching format. But that station does not have a very good signal. Salem had plans to acquire KQIN's daytime-only signal on 800 AM and improve it, making it a place to relocate KGNW. In the mid-1980s, the Federal Communications Commission relaxed rules that restricted lesser-class stations on Class A, clear channel frequencies. Fort Worth and Seattle are separated by more than 2,000 miles (3,200 km). So Salem Media engineers applied to move KQIN to 820 AM, even though WBAP 820 Fort Worth

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1012-465: Is the product of the torque τ and angular velocity ω , P ( t ) = τ ⋅ ω , {\displaystyle P(t)={\boldsymbol {\tau }}\cdot {\boldsymbol {\omega }},} where ω is angular frequency , measured in radians per second . The ⋅ {\displaystyle \cdot } represents scalar product . In fluid power systems such as hydraulic actuators, power

1058-523: Is the rate at which electrical work is performed when a current of one ampere (A) flows across an electrical potential difference of one volt (V), meaning the watt is equivalent to the volt-ampere (the latter unit, however, is used for a different quantity from the real power of an electrical circuit). 1   W = 1   V ⋅ A . {\displaystyle \mathrm {1~W=1~V{\cdot }A} .} Two additional unit conversions for watt can be found using

1104-543: The HD Radio format. KGNW airs a mix of local preachers and national Christian leaders. They include David Jeremiah , Chuck Swindoll , Jim Daly , Alistair Begg , Greg Laurie , John MacArthur , J. Vernon McGee and Charles Stanley . Two secular programs are also heard from Eric Metaxas and Jay Sekulow . KGNW uses a brokered programming model. Hosts pay for their time on the station and may ask for donations to their ministries during their shows. National news

1150-578: The International System of Units (SI), equal to 1 joule per second or 1 kg⋅m ⋅s . It is used to quantify the rate of energy transfer . The watt is named in honor of James Watt (1736–1819), an 18th-century Scottish inventor , mechanical engineer , and chemist who improved the Newcomen engine with his own steam engine in 1776. Watt's invention was fundamental for the Industrial Revolution . When an object's velocity

1196-408: The International System of Units , the unit of power is the watt , equal to one joule per second. Power is a scalar quantity. Specifying power in particular systems may require attention to other quantities; for example, the power involved in moving a ground vehicle is the product of the aerodynamic drag plus traction force on the wheels, and the velocity of the vehicle. The output power of

1242-414: The fundamental theorem of calculus , we know that P = d W d t = d d t ∫ Δ t F ⋅ v d t = F ⋅ v . {\displaystyle P={\frac {dW}{dt}}={\frac {d}{dt}}\int _{\Delta t}\mathbf {F} \cdot \mathbf {v} \,dt=\mathbf {F} \cdot \mathbf {v} .} Hence

1288-424: The mechanical advantage of the system (output force per input force) is given by M A = F B F A = v A v B . {\displaystyle \mathrm {MA} ={\frac {F_{\text{B}}}{F_{\text{A}}}}={\frac {v_{\text{A}}}{v_{\text{B}}}}.} The similar relationship is obtained for rotating systems, where T A and ω A are

1334-562: The FM band, KQIN changed to a Beautiful Music format in 1977. But that put it in competition with such FM easy listening stations as 94.1 KEUT (now KSWD), 98.9 KEZX (now KPNW-FM ), 100.7 KSEA (now KKWF ) and 103.7 KBRD (now KHTP ). KQIN also aired Christian radio programs as well as old-time radio dramas and comedies. KQIN changed to an Adult Contemporary music format in 1983. On September 19, 1984, Salem Communications acquired 1150 AM in Seattle and changed its call letters to KGNW. Salem

1380-470: The above equation and Ohm's law . 1   W = 1   V 2 / Ω = 1   A 2 ⋅ Ω , {\displaystyle \mathrm {1~W=1~V^{2}/\Omega =1~A^{2}{\cdot }\Omega } ,} where ohm ( Ω {\displaystyle \Omega } ) is the SI derived unit of electrical resistance . The watt

1426-421: The average power P avg over that period is given by the formula P a v g = Δ W Δ t . {\displaystyle P_{\mathrm {avg} }={\frac {\Delta W}{\Delta t}}.} It is the average amount of work done or energy converted per unit of time. Average power is often called "power" when the context makes it clear. Instantaneous power

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1472-583: The beginning and end of the path along which the work was done. The power at any point along the curve C is the time derivative: P ( t ) = d W d t = F ⋅ v = − d U d t . {\displaystyle P(t)={\frac {dW}{dt}}=\mathbf {F} \cdot \mathbf {v} =-{\frac {dU}{dt}}.} In one dimension, this can be simplified to: P ( t ) = F ⋅ v . {\displaystyle P(t)=F\cdot v.} In rotational systems, power

1518-515: The energy company Ørsted A/S uses the unit megawatt for produced electrical power and the equivalent unit megajoule per second for delivered heating power in a combined heat and power station such as Avedøre Power Station . When describing alternating current (AC) electricity, another distinction is made between the watt and the volt-ampere . While these units are equivalent for simple resistive circuits , they differ when loads exhibit electrical reactance . Radio stations usually report

1564-611: The force is variable over a three-dimensional curve C , then the work is expressed in terms of the line integral: W = ∫ C F ⋅ d r = ∫ Δ t F ⋅ d r d t   d t = ∫ Δ t F ⋅ v d t . {\displaystyle W=\int _{C}\mathbf {F} \cdot d\mathbf {r} =\int _{\Delta t}\mathbf {F} \cdot {\frac {d\mathbf {r} }{dt}}\ dt=\int _{\Delta t}\mathbf {F} \cdot \mathbf {v} \,dt.} From

1610-523: The formula is valid for any general situation. In older works, power is sometimes called activity . The dimension of power is energy divided by time. In the International System of Units (SI), the unit of power is the watt (W), which is equal to one joule per second. Other common and traditional measures are horsepower (hp), comparing to the power of a horse; one mechanical horsepower equals about 745.7 watts. Other units of power include ergs per second (erg/s), foot-pounds per minute, dBm ,

1656-731: The maximum performance of a device in terms of velocity ratios determined by its physical dimensions. See for example gear ratios . The instantaneous electrical power P delivered to a component is given by P ( t ) = I ( t ) ⋅ V ( t ) , {\displaystyle P(t)=I(t)\cdot V(t),} where If the component is a resistor with time-invariant voltage to current ratio, then: P = I ⋅ V = I 2 ⋅ R = V 2 R , {\displaystyle P=I\cdot V=I^{2}\cdot R={\frac {V^{2}}{R}},} where R = V I {\displaystyle R={\frac {V}{I}}}

1702-460: The maximum power output it can achieve at any point in time. A power station's annual energy output, however, would be recorded using units of energy (not power), typically gigawatt hours. Major energy production or consumption is often expressed as terawatt hours for a given period; often a calendar year or financial year. One terawatt hour of energy is equal to a sustained power delivery of one terawatt for one hour, or approximately 114 megawatts for

1748-414: The path C and v is the velocity along this path. If the force F is derivable from a potential ( conservative ), then applying the gradient theorem (and remembering that force is the negative of the gradient of the potential energy) yields: W C = U ( A ) − U ( B ) , {\displaystyle W_{C}=U(A)-U(B),} where A and B are

1794-488: The power of their transmitters in units of watts, referring to the effective radiated power . This refers to the power that a half-wave dipole antenna would need to radiate to match the intensity of the transmitter's main lobe . The terms power and energy are closely related but distinct physical quantities. Power is the rate at which energy is generated or consumed and hence is measured in units (e.g. watts) that represent energy per unit time . For example, when

1840-580: The product of a torque on a shaft and the shaft's angular velocity. Mechanical power is also described as the time derivative of work. In mechanics , the work done by a force F on an object that travels along a curve C is given by the line integral : W C = ∫ C F ⋅ v d t = ∫ C F ⋅ d x , {\displaystyle W_{C}=\int _{C}\mathbf {F} \cdot \mathbf {v} \,dt=\int _{C}\mathbf {F} \cdot d\mathbf {x} ,} where x defines

1886-488: The pulse length τ {\displaystyle \tau } such that P 0 τ = ε p u l s e {\displaystyle P_{0}\tau =\varepsilon _{\mathrm {pulse} }} so that the ratios P a v g P 0 = τ T {\displaystyle {\frac {P_{\mathrm {avg} }}{P_{0}}}={\frac {\tau }{T}}} are equal. These ratios are called

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1932-744: The torque and angular velocity of the input and T B and ω B are the torque and angular velocity of the output. If there are no losses in the system, then P = T A ω A = T B ω B , {\displaystyle P=T_{\text{A}}\omega _{\text{A}}=T_{\text{B}}\omega _{\text{B}},} which yields the mechanical advantage M A = T B T A = ω A ω B . {\displaystyle \mathrm {MA} ={\frac {T_{\text{B}}}{T_{\text{A}}}}={\frac {\omega _{\text{A}}}{\omega _{\text{B}}}}.} These relations are important because they define

1978-569: The unit of power. In the electric power industry , megawatt electrical ( MWe or MW e ) refers by convention to the electric power produced by a generator, while megawatt thermal or thermal megawatt (MWt, MW t , or MWth, MW th ) refers to thermal power produced by the plant. For example, the Embalse nuclear power plant in Argentina uses a fission reactor to generate 2,109 MW t (i.e. heat), which creates steam to drive

2024-570: The unit within the existing system of practical units as "the power conveyed by a current of an Ampère through the difference of potential of a Volt". In October 1908, at the International Conference on Electric Units and Standards in London, so-called international definitions were established for practical electrical units. Siemens' definition was adopted as the international watt. (Also used: 1 A × 1 Ω.) The watt

2070-622: The work done is defined as W = F ⋅ x {\displaystyle W=\mathbf {F} \cdot \mathbf {x} } . In this case, power can be written as: P = d W d t = d d t ( F ⋅ x ) = F ⋅ d x d t = F ⋅ v . {\displaystyle P={\frac {dW}{dt}}={\frac {d}{dt}}\left(\mathbf {F} \cdot \mathbf {x} \right)=\mathbf {F} \cdot {\frac {d\mathbf {x} }{dt}}=\mathbf {F} \cdot \mathbf {v} .} If instead

2116-420: Was defined as equal to 10 units of power in the practical system of units. The "international units" were dominant from 1909 until 1948. After the 9th General Conference on Weights and Measures in 1948, the international watt was redefined from practical units to absolute units (i.e., using only length, mass, and time). Concretely, this meant that 1 watt was defined as the quantity of energy transferred in

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