# Mass and Density

Mass is energy or momentum which is organized about a central axis.

Density is the ratio of mass to volume, the number of entities in a system per volume.

The mass and density of a body determines its size and weight, while the shape of a body is determined by the spatial arrangement of its parts.

Scale is a relative measure of the mass and density of a body, which is usually measured in relation to other bodies of different mass and density.

A moving body travels at a rate which is inversely proportional to its mass and density. Under the same conditions, the greater the mass and density of a moving body, the slower the time rate of travel.

Normally, a deer will run faster than an elephant, while an atom or molecule will spin faster than a planet or star.

Some forms of energy have no mass or density, but result from particle interactions which transfer energy from one body to another. In the propagation of a wave motion, the energy of the wave is transferred from one particle to the next through a series of collisions.

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The very stone one kicks with one’s boot will outlast Shakespeare. – Virginia Woolf