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Wednesday August 23rd 2017

Parabola

A parabola (/pəˈræbÉ™lÉ™/; plural parabolas or parabolae, adjective parabolic, from Greek: παραβολή) is a two-dimensional, mirror-symmetrical curve, which is approximately U-shaped when oriented as shown in the diagram below, but which can be in any orientation in its plane. It fits any of several superficially different mathematical descriptions which can …read more

Pentagon

In geometry, a pentagon (from the Greek pente and gonia, meaning five and angle) is any five-sided polygon. A pentagon may be simple or self-intersecting. The sum of the internal angles in a simple pentagon is 540°. A pentagram is an example of a self-intersecting pentagon.

Regular pentagons

In a regular pentagon, all sides are equal in length and each interior angle is 108°. A regular pentagon has five lines of reflectional symmetry, and rotational symmetry of order 5 (through 72°, 144°, 216° and 288°). Its Schläfli symbol is {5}. The diagonals of a regular pentagon are in …read more

Polygon

In geometry, a polygon /ˈpÉ’lɪɡɒn/ is traditionally a plane figure that is bounded by a finite chain of straight line segments closing in a loop to form a closed chain or circuit. These segments are called its edges or sides, and the points where two edges meet are the polygon’s vertices (singular: vertex) or corners. …read more

Ancient Roman units of measurement

The ancient Roman units of measurement were built on the Hellenic system with Egyptian, Hebrew, and Mesopotamian influences. The Roman units were comparatively consistent and well documented.

Length

The basic unit of Roman linear measurement was the pes or Roman foot. Investigation of its relation to the English foot goes back at least to 1647, when John Greaves published his Discourse on the Romane foot. Greaves visited Rome in 1639, and measured, among other things, the foot measure on the tomb of Titus Statilius Aper, that on the statue of Cossutius formerly in the gardens of Angelo …read more

Thai units of measurement

Thai units of measurement

Thailand adopted the metric system on 17 December 1923. However, old Thai units are still in common use, especially for measurements of land.

Before metrication, the traditional system of measurement used in Thailand employed anthropic units. Some of these units are still in use, albeit standardised to SI/metric measurements. When the Royal Thai Survey Department began cadastral survey in 1896, Director R. W. Giblin, F.R.G.S., noted, “It so happens that 40 metres or 4,000 centimetres are equal to one sen,” so all cadastral plans are plotted, drawn, and printed to a scale of 1:4,000. The square wa, ngan and …read more

Hindu units of time

Hindu units of time

The Hindu religious scriptures such as the Vedas and Puraṇas describe a massive range of units of Kala measurements, spanning right from Paramaṇu (time length of about 17 microseconds) to the Maha-Manvantara (311.04 trillion years). According to these texts, the creation and destruction of the universe is a cyclic process, which repeats itself forever. Each cycle starts with the birth and expansion (lifetime) of the universe equaling 311.04 trillion years, followed by its complete annihilation (which also prevails for the same duration).The current Universe was created in Padma kalpa, the last day Kalpa of 50 …read more

Obsolete Polish units of measurement

Obsolete Polish units of measurement

The traditional Polish units of measurement included two uniform yet distinct systems of weights and measures, as well as a number of related systems borrowed from neighbouring states. The first attempt at standardisation came with the introduction of the so-called Old Polish measurement [system], also dubbed the Warsaw system, introduced by a royal decree of December 6, 1764. The system was later replaced by the so-called New Polish measurement [system] introduced on January 1, 1819.

The traditional Polish systems of weights and measures were later replaced with those of surrounding nations (due to the Partitions of Poland), only to …read more

Dutch units of measurement

The Dutch units of measurement used today are those of the metric system. Before the 19th century, a wide variety of different weights and measures were used by the various Dutch towns and provinces. Despite the country’s small size, there was a lack of uniformity. During the Dutch Golden Age, these weights and measures accompanied the Dutch to the farthest corners of their colonial empire, including South Africa, New Amsterdam and the Dutch East Indies. Units of weight included the pond, ons and last. There was also an apothecaries’ system of weights. The mijl and roede were measurements of distance. …read more

Centimetre–gram–second system of units

Centimetreâ€
For a topical guide to this subject, see Outline of the metric system.

The centimetre—gram—second system of units (abbreviated CGS or cgs) is a variant of the metric system based on the centimetre as the unit of length, the gram as the unit of mass, and the second as the unit of time. All CGS mechanical units are unambiguously derived from these three base units, but there are several different ways of extending the CGS system to cover electromagnetism.

The CGS system has been largely supplanted by the MKS system based on the metre, kilogram, and second, which …read more

Planck units

Planck units

In physics, Planck units are physical units of measurement defined exclusively in terms of five universal physical constants listed below, in such a manner that these five physical constants take on the numerical value of 1 when expressed in terms of these units. Planck units have profound significance for theoretical physics since they elegantly simplify several recurring algebraic expressions of physical law by nondimensionalization. They are particularly relevant in research on unified theories such as quantum gravity.

Overview

Originally proposed in 1899 by German physicist Max Planck, these units are also known as natural units because the origin …read more

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Latest Topics

Parabola

A parabola (/pəˈræbələ/; plural parabolas or parabolae, adjective parabolic, from Greek: [Read More]

Pentagon

In geometry, a pentagon (from the Greek pente and gonia, meaning five and angle) is any five-sided polygon. A pentagon [Read More]

Polygon

In geometry, a polygon /ˈpɒlɪɡɒn/ is traditionally a plane figure that is bounded by a [Read More]

Ancient Roman units of measurement

The ancient Roman units of measurement were built on the Hellenic system with Egyptian, Hebrew, and Mesopotamian [Read More]

Thai units of measurement

Thailand adopted the metric system on 17 December 1923. However, old Thai units are still in common use, especially for [Read More]

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