Compactness measureCompactness measure is a numerical quantity representing the degree to which a shape is . The circle and the sphere are the most compact planar and solid shapes, respectively. PropertiesVarious compactness measures are used.
SphereA sphere (from Ancient Greek (sphaîra)'ball') is a surface analogous to the circle, a curve. In solid geometry, a sphere is the set of points that are all at the same distance r from a given point in three-dimensional space. That given point is the center of the sphere, and the distance r is the sphere's radius. The earliest known mentions of spheres appear in the work of the ancient Greek mathematicians. The sphere is a fundamental surface in many fields of mathematics.
Physical objectIn natural language and physical science, a physical object or material object (or simply an object or body) is a collection of matter, usually contiguous, with a defined boundary, that exists in space and time. It is usually contrasted with abstract objects and mental objects. Also in common usage, an object is not constrained to consist of the same collection of matter. Atoms or parts of an object may change over time.
Ball (bearing)Bearing balls are special highly spherical and smooth balls, most commonly used in ball bearings, but also used as components in things like freewheel mechanisms. The balls themselves are commonly referred to as ball bearings. This is an example of a synecdoche. The balls come in many different grades. These grades are defined by bodies such as the American Bearing Manufacturers Association (ABMA), a body which sets standards for the precision of bearing balls.
RoundnessRoundness is the measure of how closely the shape of an object approaches that of a mathematically perfect circle. Roundness applies in two dimensions, such as the cross sectional circles along a cylindrical object such as a shaft or a cylindrical roller for a bearing. In geometric dimensioning and tolerancing, control of a cylinder can also include its fidelity to the longitudinal axis, yielding cylindricity.
Three-dimensional spaceGeometric model of the physical spaceA representation of a three-dimensional Cartesian coordinate systemIn geometry, a three-dimensional (3D) space is a mathematical space in which three values (termed coordinates) are required to determine the position of a point. Alternatively, it can be referred to as 3-space or, rarely, tri-dimensional space.
Ball bearingA ball bearing is a type of rolling-element bearing that uses balls to maintain the separation between the bearingraces. The purpose of a ball bearing is to reduce rotational friction and support radial and axial loads. It achieves this by using at least two races to contain the balls and transmit the loads through the balls. In most applications, one race is stationary and the other is attached to the rotating assembly (e.g., a hub or shaft).
Cross section (geometry)In geometry and science, a cross section is the non-empty intersection of a solid body in three-dimensional space with a plane, or the analog in higher-dimensional spaces. Cutting an object into slices creates many parallel cross sections.Quality (business)In business, engineering, and manufacturing, quality has a pragmatic interpretation as the conformity of something (goods or services); it is defined as being suitable for the intended purpose (fitness for purpose) while satisfying customer expectations. Quality may be a perceptual, conditional, and somewhat subjective attribute and may be understood differently by different people.
CylinderA cylinder (from Ancient Greek (kúlindros)'roller, tumbler') has traditionally been a three-dimensional solid, one of the most basic of curvilinear geometric shapes. In elementary geometry, it is considered a prism with a circle as its base. A cylinder may also be defined as an infinite curvilinear surface in various modern branches of geometry and topology.
Plane (mathematics)In mathematics, a plane is a two-dimensional space or flatsurface that extends indefinitely. A plane is the two-dimensional analogue of a point (zero dimensions), a line (one dimension) and three-dimensional space. When working exclusively in two-dimensional Euclidean space, the definite article is used, so theEuclidean plane refers to the whole space. Several notions of a plane may be defined.Shaft (mechanical engineering)In mechanical engineering, a shaft is a rotating machine element, usually circular in cross section, which is used to transmit power from one part to another, or from a machine which produces power to a machine which absorbs power.
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