Fundamental and derived units in SI System
Let's break down the concepts of fundamental and derived units in the SI (International System of Units) system and provide an overview of what the SI system is.
What is SI System?
The International System of Units (SI) is the modern form of the metric system used in science, engineering, and everyday commerce worldwide. It is a comprehensive and coherent system of measurement that is based on fundamental constants of nature, providing a standardized framework for expressing physical quantities.
Fundamental Units in SI:
The SI system has seven fundamental units, which are the building blocks for all other units. These fundamental units are used to express seven basic physical quantities. Here are the seven fundamental units:
1. Meter (m): Unit of length. The meter is the unit of length. It is currently defined as the distance traveled by light in a vacuum during a specific fraction (1/299,792,458) of a second..
2. Kilogram (kg): Unit of mass. The kilogram is the unit of mass. Originally defined as the mass of a specific platinum-iridium alloy cylinder kept at the International Bureau of Weights and Measures, it is now defined in terms of fundamental constants.
3. Second (s): Unit of time. It is defined by the vibrations of a cesium-133 atom.
4. Ampere (A): Unit of electric current. It is defined in terms of the force between two current-carrying conductors.
5. Kelvin (K): Unit of temperature. It is defined using the Boltzmann constant and the thermodynamic temperature of the triple point of water.
6. Mole (mol): Unit of amount of substance. It is defined by Avogadro's number, which is the number of atoms in 0.012 kilograms of carbon-12.
7. Candela (cd): Unit of luminous intensity. It is defined using the power of monochromatic radiation of a specific frequency.
Derived Units in SI:
Derived units are combinations of fundamental units that express other physical quantities. These units are derived from the fundamental units and are used to measure a wide range of parameters. Some examples of derived units include:
1. Newton (N): Unit of force, derived from mass, length, and time.
2. Joule (J): Unit of energy, derived from mass, length, and time.
3. Watt (W): Unit of power, derived from energy and time.
4. Pascal (Pa): Unit of pressure, derived from force and area.
5. Volt (V): Unit of electric potential, derived from energy and electric charge.
These fundamental units provide a standardized and internationally accepted system for expressing various physical quantities, forming the foundation for both scientific and engineering measurements. All other units in the SI system are derived from combinations of these fundamental units.
Significance for Engineering College Students:
Understanding the SI system is fundamental for engineering students as it provides a standardized and coherent way to express and communicate measurements. Engineers often work with a variety of physical quantities in their field, and the SI system ensures consistency and accuracy in these measurements. It also facilitates communication and collaboration across different disciplines and countries, as the SI units are universally recognized and accepted. Engineering calculations, designs, and experiments are all based on the principles of the SI system, making it an essential component of an engineer's education and professional practice.
