Cerium (Ce)

— a chemical element, atomic number $58$, atomic mass $140.12$. Metal steel gray color, density $6770\ \mathrm{kg} / \mathrm{m}^{3}$, melting point: $795\ ^{\circ} \! {\mathrm{C}}$.

Central Force

— a force applied to a material point (the body), the line of action which in any position of a point (the body) pass through the same fixed point, called the center of power. Such conditions are satisfied, ie., The forces of gravity, Coulomb force (see. Coulomb’s law).

Center of Gravity

— always linked to a solid point through which the resultant of the gravitational forces acting on all the particles of the body (at any position of the body in space). Provisions C.of g. solid state coincides with the position of its center of mass.

Center of Inertia, Center of Mass

— geometrical point characterizing the distribution of mass in the mechanical system. The radius vector C.of i. system consisting of $n$ material points, equal $$ \vec{r}_{c i }=\frac{\sum_{i=1}^{n} m_{i} \vec{r}_{i}}{\sum_{i=1}^{n} m_{i}} $$ where $m_{i}$ and $\vec{r}_{i}$ — mass and radius vector of $i$ -th point, and $\sum_{i=1}^{n} m_{i}=M$ — the mass of the system. When moving body (system) his C.of i.

Cesium (Cs)

— a chemical element, atomic number $55$, atomic mass $132.9054$. The soft metal with golden-yellow hue, density $1900\ \mathrm{kg} / \mathrm{m}^{3}$, melting point: $28.5\ ^{\circ} \! {\mathrm{C}}$.

Chromatic Aberration

— one of the aberrations of the optical system, which is caused by dispersion of light in optical systems due to their use in non-monochromatic (white) light. Ch. a. manifested in the formation of the image colored contours.

Chromium (Cr)

— a chemical element, atomic number $24$, atomic mass $51.996$. The solid metal is steel-gray in color, density $7190\ \mathrm{kg} / \mathrm{m}^{3}$, melting point: $1903\ ^{\circ} \! {\mathrm{C}}$.