# length

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## length

1. Prosody Phonetics the metrical quantity or temporal duration of a vowel or syllable
2. the distance from one end of a rectangular swimming bath to the other
3. Prosody the quality of a vowel, whether stressed or unstressed, that distinguishes it from another vowel of similar articulatory characteristics. Thus in English beat is of greater length than in English bit
4. Cricket the distance from the batsman at which the ball pitches
5. Bridge a holding of four or more cards in a suit

## Length

A one-dimensional extension in space. Length is one of the three fundamental physical quantities, the others being mass and time. It can be measured by comparison with an arbitrary standard; the specific one in most common usage is the international meter. In 1983, at the meeting of the Conférence Général des Poids et Mésures, the meter was redefined in terms of time and the speed of light: “The meter is the length of the path traveled by light in vacuum during a time interval of 1/299 792 458 of a second.” This definition defines the speed of light to be exactly 299 792 458 m/s, and defines the meter in terms of the most accurately known quantity, the second. See Light, Mass, Time

## Length

a numerical characteristic of the extent of curves. The concept of length is defined differently for different cases. (1) The length of a line segment is the distance between its end points, measured by some segment taken as a unit of length. (2) The length of a polygonal line is the sum of the lengths of its components. (3) The length of a simple arc is the limit of the lengths of polygonal lines inscribed in the arc, when the number of components increases indefinitely and the maximum length of the components tends to zero. (4) The length of a continuous curve consisting of a finite number of simple arcs is equal to the sum of the lengths of these arcs. For example, the circumference of a circle can be obtained as the limit of the perimeters of inscribed regular polygons when the number of their sides is doubled indefinitely; it is equal to 2πR where R is the radius of the circle. Any continuous curve has finite or infinite length. If its length is finite, then the curve is said to be rectifiable. The graph (see Figure 1) of the function

for 0 <x ≤ 1 and f(x) = 0 when x = 0 is an example of a nonrectifiable curve; here the lengths of the inscribed polygonal lines increase beyond all bound as the length of the components tend to zero. If the equation of a plane curve has the form y =f(x) (a ^ x ^ b)m rectangular coordinates and the function f(x) has a continuous derivative f’(x), then the length of the curve is given by the integral

The length of a curve given in parametric form and the length of a space curve can be expressed in a similar manner.

Figure 1

To calculate the length of a curve the mathematicians of antiquity essentially used lengths of polygonal lines and passage to the limit. For them, however, such passage to the limit was only a method for calculating the length of a curve and not for defining the concept of the length of a curve, since they apparently perceived the latter as one of the elementary mathematical concepts. The necessity of defining the length of a curve became clear only in the first half of the 19th century. A full elucidation of the problem was achieved by C. Jordan. In differential geometry the length of a curve is also defined on a surface or in an arbitrary Riemannian space.

### REFERENCES

Lebesgue, H. Ob izmerenii velichin, 2nd ed. Moscow, 1960. (Translated from French.)
Fikhtengol’ts, G. M. Kurs differentsial’nogo i integral’nogo ischisleniya, 7th ed. vol. 2. Moscow, 1969.

## length

[leŋkth]
(mechanics)
Extension in space.
References in periodicals archive ?
These angles were chosen so that there was a difference in muscle length [1] and comparable to previous research [3].
Muscle strength, muscle length, and three-dimensional lower extremity kinematics and kinetics were collected prior to the 6-week intervention and no later than two-weeks after completion of the intervention for both teams.
In terms of physical risk factors, there were between-group differences in favour of the experimental group in hamstring and iliopsoas muscle length and neural mobility and these were largely maintained 3 months later whereas there were no statistically significant between-group differences in rectus femoris length, lumbar stability or proprioception (Table 2).
20) A study of the changes in the gonial region induced by alterations of the masseter muscle length concluded that blood supply and function influence the shape of the gonial region.
the acting of gripping devices for rigid bodies for which the variation of muscle length is very small, and the force is determined, linear, depending on the pressure;
Gradual stimulation of the musculature with progressively more difficult workloads reduces the inhibitory impulses picked-up by the sensory receptors that monitor changes in muscle length.
The machine, which Jack had paid for himself and was using daily, helps to maintain blood pressure, bone strength and muscle length.
Assessments of the complaint included such aspects as visual signs of dysfunction, piriformis impingement analysis, piriformis muscle length test and piriformis strength test.
Spindles are sensitive to changes in tension brought about by increases in muscle length.
Taylor, Waring and Brashear (1995) studied the hamstring muscle length of 24 subjects.
Cinematographic analysis of the passive straight leg raising test for hamstring muscle length.

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