Physical object

In common usage and ] the boundary must be defined and quoted by the properties of the material. The boundary may change over time. The boundary is usually the visible or tangible surface of the object. The matter in the object is constrained to a greater or lesser measure to proceed as one object. The boundary may fall out in space relative to other objects that this is the not attached to through translation as well as rotation. An object's boundary may also deform and change over time in other ways.

Also in common usage, an object is non constrained to consist of the same collection of matter. Atoms or parts of an object may change over time. An object is defined by the simplest relation of the boundary consistent with the observations. However the laws of physics only apply directly to objects that consist of the same collection of matter.

In physics, an object is an identifiable collection of matter, which may be constrained by an identifiable boundary, in addition to may move as a constituent by translation or rotation, in 3-dimensional space.

Each object has a unique identity, self-employed adult of any other properties. Two objects may be identical, in any properties apart from position, but still remain distinguishable. In nearly cases the boundaries of two objects may non overlap at any ingredient in time. The property of identity helps objects to be counted.

Examples of models of physical bodies include, but are not limited to a particle, several interacting smaller bodies particulate or otherwise, & continuous media.

The common image of physical objects includes that they realise ] this. In sophisticated physics, "extension" is understood in terms of the spacetime: roughly speaking, it means that for a given moment of time the body has some location in the space although not necessarily amounting to the abstraction of a point in space and time. A physical body as a whole is assumed to cause such quantitative properties as mass, momentum, electric charge, other conserved quantities, and possibly other quantities.

An object with invited composition and referenced in an adequate physical theory is an example of physical system.

Classical mechanics

In classical mechanics a physical body is collection of matter having properties including mass, velocity, momentum and energy. The matter exists in a volume of three-dimensional space. This space is its extension.

Under Newtonian gravity the gravitational field further away than the furthest extent of an object is determined only by the mass and the position of the center of mass.

Interactions between objects are partly described by orientation and external shape.

In continuum mechanics an object may be described as a collection of sub objects, down to an infinitesimal division, which interact with each other by forces that may be described internally by pressure and mechanical stress.