factor, in arithmetic, any number that divides a given number evenly, i.e., without any remainder. The factors of 12 are 1, 2, 3, 4, 6, and 12. Similarly in algebra, any one of the algebraic expressions multiplied by another to form a product is a factor of that product, e.g., a+b and a-b are factors of a²-b ², since (a+b)(a-b)=a²-b². In general, if r is a root of a polynomial equation f(x)=0, then (x-r) is a factor of the polynomial f(x).

Still-air temperature that would have the same cooling effect on exposed skin as a given combination of temperature and wind speed. As the wind speed increases, the wind chill equivalent temperature decreases; e.g., an air temperature of 30 °F (–1.1 °C) with a wind speed of 20 mph (32.2 kph) produces a wind chill of 17 °F (–8 °C). Wind chill is often included in weather reports to describe how cold it feels.

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In multiplication, one of two or more numerical or algebraic components of a product. A whole number's factors are the whole numbers that divide evenly into it (e.g., 1, 2, 3, 4, 6, and 12 are factors of 12). To factor a counting number means to break it down into its prime number factors. To factor a polynomial is to find its prime polynomial factors, a basic procedure for solving algebraic equations. According to the fundamental theorem of arithmetic, the prime factorization of any number or polynomial is unique.

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Telecommunications

In telecommunication, the term k-factor has the following meanings:

1. In tropospheric radio propagation, the ratio of the effective Earth radius to the actual Earth radius.

Note: The k-factor is approximately 4/3.

2. In ionospheric radio propagation, a correction factor that (a) is applied in calculations related to curved layers, and (b) is a function of distance and the real height of ionospheric reflection.

3. In laser diode technology, it describes the exceed spontaneous emission noise in gain-guided lasers.

Source: From Federal Standard 1037C and from MIL-STD-188

Fire protection engineering

In fire protection engineering, the term k-factor has the following meaning:

The flow rate of a sprinkler is given by $dot\; m\_w\; =\; Ksqrt\; p$, where p is the operating pressure, usually given in bar. K is the K-factor commonly given in units of $L/min/sqrttext\{bar\}$.

The units conveniently allow $dot\; m\_w$ to stand for either the mass flow rate in kg/min or the volumetric flow rate in L/min.

It is a factor to find the effective length of the column in structural engineering.

Sheet metal engineering

In sheet metal engineering, the term k-factor has the following meaning:

During bending the inner surface of the bend is subjected to compression while the outer surface is subjected to tension. However there is a layer in between which is free from any forces and thus its length remains the same. This is called the neutral axis (N.A ). The radius of this layer of metal is called the neutral bend arc radius (NBAR )and is defined as the inside bend radius plus a percentage(K-factor ) of the metal thickness.

NBAR = BR + (T × K-factor)

The K-Factor (K) depends on the material, the type of bending operation (coining, air-bending), the ratio of the bend radius to the metal thickness (R/T) and is typically between 0.3 to 0.5. For most types of steels it is around 0.33 to 0.4

Insurance

In actuarial work, the term K-factor refers to the ratio of deferrable expenses to the Estimated Gross Profits. It is an important measurement used to manage the deferrals allowed in insurance accounting.

Oil heating

Degree day system

The degree day system is based on the amount of fuel a customer has consumed between two or more deliveries and the high and low outdoor temperatures during the same period. A degree day is defined as one degree of temperature below 65°F in the average temperature of one day. In other words, to arrive at the number of degree days in one day, the official high and low temperatures for that day must be obtained. The two figures are then averaged, and the number of units this average is below 65°F is the number of degree days for that day. For example, if for Tuesday, November 3, the high temperature is 70°F and the low is 54°F, the average is found by adding 70 and 54, which equals 124, and then dividing by 2. The resultant figure is 62, and by subtracting 62 from 65, it is determined that there were three (3) degree days that day.

K-factor

To determine usage or "K" factor, first compute the number of gallons of fuel oil used in a given period. Then, using the cumulative total of degree days for the same period of time, you can figure the "K" factor, or the number of degree days that one gallon of fuel will last at the current rate of consumption. This factor is arrived at by dividing the number of degree days in any given period by the total number of gallons of fuel consumed during the same period. For example, if during the month of November your furnace burns 200 gallons of fuel oil and assuming that we had 300 degree days, your "K" factor would be 300 divided by 200, which equals 1.5. In other words, each gallon of fuel oil provides you with 11/2 degree days of heat.

The next step is to determine how many days' supply remain in the tank once it has been filled. From the total tank capacity, you can subtract a number of reserve gallons which depends, of course, upon the size of the tank. Then multiply the number of gallons of usable fuel by the "K" factor, and you have what is known as the Degree Days of Usable Fuel. Using this figure, oil companies can arrive at the degree day of your next scheduled delivery.

Physics

The term k-factor is sometimes used to express the thermal conductivity of a material, that is the property of a material that indicates its ability to conduct heat.

Fuel Flow Metering

For aircraft fuel flow meters, k-factor refers to the number of pulses expected for every one gallon of fuel passing through the transducer at optimum cruise settings. It is expressed in thousandths (e.g., 29.6 = 29,600 pulses).

Centrifugation

In centrifugation the k-factor represents the clearing factor of a centrifuge rotor at maximum rotation speed. This factor can be used to determine the time required for pelleting a fraction with a known sedimentation coefficient.