Concept in Definition ABC

According to the use and the context in which it is used, the term Metro has several references.

The most widespread says that metro is the Unit length of the International System of Units.
According to what the International Office of Weights and Measures tells us, the great specialist in this regard, one meter is the distance that travels light in a vacuum for an interval of 1 / 299,792,458 of a second.

Originally this unit of length was created at the request of the French Academy of Sciences in 1791 and defined conveniently as the ten millionth part of the distance that separates the pole from the line corresponding to the equator land.

On the other hand, also with the word meter, the measuring instrument that has the length of this unit and its dividers marked. Also known as tape measure, the meter is used in measurement of distances and is built either in a thin sheet of steel chrome, aluminum, or, the most modern, through a weave of carbon fibers joined through a

polymer Teflon. The most used meters are those of 5, 10, 15, 20, 25, 30, 50 and 100 meters.

The meters of 50 and 100 meters are also known as a surveyor and are made only of steel, since the force used to tension them is such that otherwise, if they were made of a material less resistant to steel, it could produce the extension of the same, an effect of course detrimental when achieving the objective that is accuracy in the measurement. In addition, they are marked with copper rivets or bronze fixed to the tape every 2 dm, while the smallest ones, on the contrary, are centimeter and millimeter with the marks and numbers painted or engraved on the surface of the tape.

Also, the word Metro turns out to be the shorthand for the term railway and underground and is therefore popularly used to refer to these means of transport so popular in most of the big cities of the world.

Then, metro is called the mass passenger transport rail systems that operate in large cities to link various areas of their city. territory municipal and also its closest surroundings. This type of transport is characterized mainly by the large number of passengers that it allows to transport and by the high frequency of schedules with those that count so that people at any time can move without inconvenience to their homes, jobs or study centers, among other places.

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