- published: 29 Dec 2011
- views: 10063913
In geometry, a cube is a three-dimensional solid object bounded by six square faces, facets or sides, with three meeting at each vertex. The cube can also be called a regular hexahedron and is one of the five Platonic solids. It is a special kind of square prism, of rectangular parallelepiped and of trigonal trapezohedron. The cube is dual to the octahedron. It has cubical symmetry (also called octahedral symmetry). It is special by being a cuboid and a rhombohedron.
The cube has four special orthogonal projections, centered, on a vertex, edges, face and normal to its vertex figure. The first and third correspond to the A2 and B2Coxeter planes.
For a cube centered at the origin, with edges parallel to the axes and with an edge length of 2, the Cartesian coordinates of the vertices are
while the interior consists of all points (x0, x1, x2) with −1 < xi < 1.
For a cube of edge length a,
As the volume of a cube is the third power of its sides a × a × a, third powers are called cubes, by analogy with squares and second powers.
Ice cubes are small, roughly cube-shaped pieces of ice, conventionally used to cool beverages. Ice cubes are sometimes preferred over crushed ice because they melt more slowly; they are standard in mixed drinks that call for ice, in which case the drink is said to be "on the rocks."
Ice cubes that are crushed or sheared into irregularly-shaped flakes may add an interesting aesthetic effect to some cocktails. Crushed ice is also used when faster cooling is desired, since the rate of cooling is governed by the number and average radius of the ice particles.
Melting ice cubes sometimes precipitate white flakes, commonly known as "floaties". This is calcium carbonate which is present in many water supplies and is completely harmless.[citation needed]
American physician and humanitarian John Gorrie built a refrigerator in 1844 with the purpose of cooling air. His refrigerator produced ice which he hung from the ceiling in a basin. Gorrie can be considered the creator of ice cubes, but his aim was not to cool drinks: he used the ice to lower the ambient room temperature. During his time, a dominant idea was that bad air quality caused disease. Therefore, in order to help treat sickness, he pushed for the draining of swamps and the cooling of sickrooms.