Hubungan Besaran Pokok dan Besaran Turunan dalam Sistem Internasional

The International System of Units (SI), commonly known as the metric system, provides a standardized framework for measuring various physical quantities. This system is built upon a foundation of seven fundamental units, known as base units, which are independent and cannot be derived from other units. These base units serve as the building blocks for defining all other units, known as derived units, which are combinations of base units. Understanding the relationship between base units and derived units is crucial for comprehending the interconnectedness of physical quantities and their measurements within the SI system.

The Foundation of Measurement: Base Units

The SI system is based on seven base units, each representing a fundamental physical quantity. These base units are:

* Meter (m): The base unit for length, representing the distance traveled by light in a vacuum in a specific time interval.

* Kilogram (kg): The base unit for mass, defined as the mass of a specific platinum-iridium cylinder kept at the International Bureau of Weights and Measures.

* Second (s): The base unit for time, defined as a specific number of cycles of radiation emitted by a cesium-133 atom.

* Ampere (A): The base unit for electric current, defined as the constant current that, if maintained in two straight parallel conductors of infinite length, of negligible circular cross-section, and placed one meter apart in vacuum, would produce between these conductors a force equal to 2 × 10⁻⁷ newton per meter of length.

* Kelvin (K): The base unit for thermodynamic temperature, defined as 1/273.16 of the thermodynamic temperature of the triple point of water.

* Mole (mol): The base unit for amount of substance, defined as the amount of substance that contains as many elementary entities as there are atoms in 0.012 kilogram of carbon-12.

* Candela (cd): The base unit for luminous intensity, defined as the luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency 540 × 10¹² hertz and that has a radiant intensity in that direction of 1/683 watt per steradian.

These base units are the foundation upon which all other units in the SI system are built.

Derived Units: Building Blocks of Measurement

Derived units are units that are defined as combinations of base units. They represent physical quantities that can be expressed in terms of the fundamental quantities represented by the base units. For example, the unit for speed, meter per second (m/s), is derived from the base units for length (meter) and time (second).

The process of deriving units involves using mathematical operations such as multiplication, division, and exponentiation on the base units. For instance, the unit for area, square meter (m²), is derived by squaring the base unit for length (meter). Similarly, the unit for volume, cubic meter (m³), is derived by cubing the base unit for length (meter).

Examples of Derived Units

Here are some examples of derived units and their corresponding base unit combinations:

* Velocity: m/s (meter per second)

* Acceleration: m/s² (meter per second squared)

* Force: N (newton) = kg⋅m/s² (kilogram meter per second squared)

* Pressure: Pa (pascal) = N/m² (newton per square meter)

* Energy: J (joule) = N⋅m (newton meter)

* Power: W (watt) = J/s (joule per second)

These examples illustrate how derived units are constructed from base units, providing a consistent and interconnected system for measuring various physical quantities.

The Importance of the Relationship

The relationship between base units and derived units is fundamental to the SI system. It ensures that all measurements are based on a common set of standards, facilitating consistency and interoperability across different fields of science, engineering, and technology. This relationship also allows for the derivation of new units as needed, expanding the scope of the SI system to encompass emerging scientific discoveries and technological advancements.

Conclusion

The International System of Units (SI) is a comprehensive and standardized system for measuring physical quantities. It is built upon a foundation of seven base units, which represent fundamental physical quantities. Derived units, which are combinations of base units, are used to measure other physical quantities. The relationship between base units and derived units is crucial for ensuring consistency, interoperability, and the ability to derive new units as needed. Understanding this relationship is essential for comprehending the interconnectedness of physical quantities and their measurements within the SI system.