A rigid box with a unique name and the following parameters:

- position: The X/Y position of the centre of mass of the box, relative to the centre of the world.
- angle: By how much the box is rotated in positive direction, that is clockwise.
- velocity: The velocity of the centre of mass of the box. Unit: metres/second.
- angular velocity: How fast the box is spinning in positive direction, that is clockwise.
- mass: Total mass of the box. This influences forces with which the box interacts with other items.
- inertia: How difficult it is to change the box's rotation.
- momentum: A fundamental quantity in mechanics that is conserved in the absence of external forces. A product of the mass and the velocity.
- angular momentum: Measure of the extent to which the box will continue to rotate unless acted upon by an external torque.
- kinetic energy: The work needed to accelerate the body of a given mass from rest to its current velocity.
- size: Defines width and height of the box.