PhysicalEntity

A physical entity is any object or system that has physical existence and can be described by physical quantities such as mass, position, and energy. In physics, this term refers to tangible objects ranging from elementary particles to macroscopic bodies. The concept contrasts with abstract entities like numbers or mathematical constructs.

In classical mechanics, a physical entity is characterized by state variables (position, velocity, orientation) and parameters (mass, inertia) and evolves under forces according to equations of motion. Depending on scale and complexity, it may be modeled as a point mass, a rigid body, an extended deformable body, or a fluid element.

In computing and simulation, PhysicalEntity is a common abstraction used to represent real objects within a virtual environment. A typical model includes physical state (pose, linear and angular velocity, linear and angular momentum) and physical properties (mass, moment of inertia, shape, material properties). Methods manipulate forces, torques, and collisions, and an integrator updates the state over time.

Applications include video games, robotics, engineering simulation, and scientific visualization. Examples include a bouncing ball, a spacecraft under thrust, a molecule modeled with interatomic forces, or a rigid car chassis in a driving simulator.

Limitations include the simplifications inherent in any model. Quantum or relativistic effects may be ignored at ordinary scales; real objects may deform, fracture, or interact with complex environments. The term remains a general descriptor rather than a fixed technical definition.