The metric system is calculated in millimeters, and the British/Imperial system is calculated in inches.
Metric system: also known as “meter system”, an international measurement and constant system that entered China after the signing of the “Sino-French Commercial Regulations” in 1858. It was founded in France.
The metric system uses meters, centimeters, decimeters, millimeters, and other measurement Units to determine the length, and seconds to determine the length of time.
The British system: It is a measurement system used in English-speaking countries such as the United Kingdom and the United States. British law stipulates that the British system is generally used in daily life, and commercial retail must use the metric system. In some aviation management such as flight altitude and runway length, the British system is still used.
Extended information:
The British unit was born out of the Roman Empire’s unit of measurement, so like the Roman Empire’s unit, agricultural production at that time was used as the unit’s benchmark.
Length unit: 1 inch = 25.4 mm, one inch is equal to the total length of three barley;
Weight unit: 1 pound = 0.45392 kilograms, one pound is equal to 7000 times the weight of a barley taken from the middle of the ear;
Volume unit (derived unit): 1 pint = 0.5506 liters, a pint of water equals one and a quarter pounds.
Area unit: 1 acre = 40470000 square centimeters.
The metric system had two important principles in its early development:
The first item is decimal for calculation. As far as a decimal is concerned, the conversion between two units only needs to be converted in multiples of ten, which can reduce its complexity.
The second principle is to use the basic unit generally accepted by ordinary people to derive other units by logical calculation. For example, length is the most acceptable unit for ordinary people. The unit of volume is equivalent to the cube of the side length, and the unit of side length is length. , so the unit of volume is the cube of the side length
The primary unit of length is feet, the primary unit of weight in pounds, the primary unit of volume is gallons, and the primary unit of temperature is degrees Fahrenheit.
