Alapmennyiséget

Alapmennyiséget is a Hungarian term that translates to "base quantity" or "fundamental quantity" in English. It refers to a set of physical quantities that are defined independently and serve as the foundation for all other physical quantities. In the International System of Units (SI), there are seven base quantities: length, mass, time, electric current, thermodynamic temperature, amount of substance, and luminous intensity.

These base quantities are not derived from other quantities; instead, they are assigned agreed-upon units. For example, the base quantity of length is assigned the unit of meter (m). Mass is assigned the kilogram (kg), and time is assigned the second (s). Electric current uses the ampere (A), thermodynamic temperature uses the kelvin (K), amount of substance uses the mole (mol), and luminous intensity uses the candela (cd).

All other physical quantities, known as derived quantities, can be expressed as combinations of these base quantities. For instance, velocity is a derived quantity, being the ratio of length to time (m/s). Force is another derived quantity, defined as mass times acceleration, where acceleration itself is derived from length and time (kg·m/s²). The concept of alapmennyiséget ensures a consistent and coherent system for measurement across all scientific disciplines.