Metric System
In everyday life, the metric system is a system of units commonly used in measurement. Metric is an adoption of the International System of Units (abbreviated SI in French), which is the modern form of the metric system. The metric system has been in use for over two centuries by more than 95 percent of the world population. The metric system’s main features are its unit names, its decimal subdivisions, and its prefixes. All metric units are related to the base unit of the particular quantity being measured, a relationship which allows users to easily convert from one unit to another, and understand relationships between different measures of the same quantity.
The basic unit of length is the meter (m). It is the distance light travels in a vacuum in 1/299,792,458th of a second. A more commonly used length is the kilometer (km), which is equal to 1000 meters. Other common metric units of length are decimeters (dm), which equal 10 cm; centimeters (cm), which equal 0.01 m; and millimeters (mm), which equal 0.001 m. Prior to 1983, the basic unit of mass was the gram (g), which is currently equal to one milliliter (ml) of water at 4°C. The kilogram (kg) is now the base unit of mass, and it is equal to1000 g. Other common metric units of mass are the milligram (mg), which equals 0.001 g; and the microgram (μg), which is equal to 0.000001 g.
The basic unit of electrical current is the ampere (A), which is equal to one coulomb (C) of charge per second. The ampere is used to measure the amount of electric current passing through a conductor. Other common metric units of electrical current are the milliampere (mA), which equals 0.001 A; and the microampere (μA), which is equal to 0.000001 A.
The basic unit of temperature is the degree Celsius (°C), which is equal to one Kelvin (K). Other common metric units of temperature are the degree Fahrenheit (°F), which is equal to 1.8°C + 32°; and the rankine (°R) ,which is equal to 1.8°C + 491.67°.
The basic unit of energy is the joule (J ), which is equal to one newton-meter. One joule is equal to the work done when a force of one newton is exerted over a distance of one meter. Other common metric units of energy are the kilojoule (kJ ), which is equal to 1000 J; and the megajoule (MJ ), which is equal to one million joules.
The basic unit of pressure is the Pascal (Pa), which is equal to one newton per square meter. Other common metric units of pressure are the bar (bar), which is equal to 1 × 105 Pa; the atmopshere (atm), which is equal to 1.01325 × 105 Pa; and the psi (psi), which is equal to 6.895 × 103 Pa.
The metric system is a very important tool for scientists, engineers, and other professionals. It allows for an easy way of discussing and comparing measurements. With the metric system, measurements can be expressed in metric units, and converted to different units when required. By understanding the metric system and its basic units, it becomes much easier to understand and use metric measurements.
