Disk (mathematics)

In geometry Geometry

Geometry arose as the field of knowledge dealing with spatial relationships.... 

, a disk is the region in a plane contained by a circle Circle

In Euclidean geometry [i], a circle is the set [i] of all points [i] in a plane at a fixed distance [i] ... 

. A disk is said to be closed or open according to whether or not it contains the circle that constitutes its boundary. In Cartesian coordinates Cartesian coordinate system

In mathematics [i], the Cartesian coordinate system is used to uniquely determine each point [i] ... 

, the open disk of center and radius R is given by the formula while the closed disk of the same center and radius is given by The area Area

Area is a physical quantity [i] expressing the size of a part of a surface [i]. ... 

 of a closed or open disk of radius R is pR2 . The ball Ball

Balls are usually hollow and spherical [i] but can be other shapes, such as ovoid [i] or solid . ... 

is the disk generalised to metric spaces. However, sometimes "disk" is used to mean "ball". In theoretical physics a disk is a rigid body which is capable of participating in collisions in a two-dimensional gas Two-dimensional gas

A two-dimensional gas is a collection of N objects which are constrained to move in a planar or other tw... 

.

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Encyclopedia

In geometry Geometry

Geometry arose as the field of knowledge dealing with spatial relationships.... 

, a disk is the region in a plane contained by a circle Circle

In Euclidean geometry [i], a circle is the set [i] of all points [i] in a plane at a fixed distance [i] ... 

.

A disk is said to be closed or open according to whether or not it contains the circle that constitutes its boundary. In Cartesian coordinates Cartesian coordinate system

In mathematics [i], the Cartesian coordinate system is used to uniquely determine each point [i]... 

, the open disk of center and radius R is given by the formula
while the closed disk of the same center and radius is given by

The area Area

Area is a physical quantity [i] expressing the size of a part of a surface [i]. ... 

 of a closed or open disk of radius R is pR² .

The ball Ball

Balls are usually hollow and spherical [i] but can be other shapes, such as ovoid [i] or solid . ... 

is the disk generalised to metric spaces. However, sometimes "disk" is used to mean "ball".

In theoretical physics a disk is a rigid body which is capable of participating in collisions in a two-dimensional gas Two-dimensional gas

A two-dimensional gas is a collection of N objects which are constrained to move in a planar or other tw... 

. Usually the disk is considered rigid so that collisions are deemed elastic Elastic collision

An elastic collision is a collision in which the total kinetic energy [i] of the colliding bodies after ... 

.

See also

• Unit disk Unit disk
  
  In mathematics [i], the open unit disk around P, is the set of points whose distance from P is l ... 
  
  , a disk with radius one
• annulus
  

Categories:

• Euclidean geometry