Mass - Weight

Mass

The mass of a body is a measure of the amount of matter of which it is made and is determined by scales. In operational terms, the mass of an object is defined as the property of an object measured by a two-arm balance. This ladder consists of a rigid rod, yoke, bearing two plates that are suspended at the ends and can be rotated around a central point, known as a shaft. If two objects on the plate have the same mass, the balance is balanced and the needle points towards the center of the balance. If two objects have different masses, the balance is tilted in favor of the larger object. To perform the measurement, the test object is placed on one plate and known mass samples on the other, to bring the indicator into the vertical position. The mass of the object is equal to the sum of the masses of the samples used. Therefore, the problem of mass measurement is solved when a sample object has been selected, its mass is taken as a unit. Therefore, the process is as follows:

• An object of unknown mass is placed on one of the scales
• Standard mass unit sitting on another plate
• The mass of the object is equal to the sum of the masses of all the sample units placed on the second plate.

Unit of measurement of mass

The unit of measurement chosen as sample is the kilogram (kg), and sub-multiples such as hectogram, gram and milligram or multiples thereof such as quintals and tons are commonly used. The kilogram refers to a sample of matter, having the mass of a platinum-iridium cylinder, 3,900 cm high and diameter, stored in Sèvres, France. By this definition, kilograms are actually equal to the mass of 1 liter of distilled water.
The unit of measurement of a physical quantity must be chosen so that it remains constant over time so that each measure can be compared with the others and always gives the same results usage is necessary. The sample found in Sèvres is always kept at the same temperature and pressure so that it does not change over time. Therefore, all 1 kg masses are copies of the standard mass.

Masses and weight, the differences

In common language, mass is often confused with weight and the kilogram is used as a unit of weight. In fact mass and weight are two very different and profoundly different sizes:
Mass is an intrinsic property of the material of which an object is made. Weight is the force with which this object is attracted to the planet on which it is located. We know that a liberated body falls to the ground from a certain height, because gravity pulls all bodies towards the center of the earth, with a force called gravity, proportional to the body mass. Weight is a force associated with mass, it is created by gravity: on Earth, on the Moon and in space, the same mass has a completely different weight.
The heavy force a body is subjected to is often called body weight: when we weigh an object, we do not measure its mass, but the force with which it is drawn to Earth. The scales used every day do not directly measure mass, they measure weight. The mass value that we read on a graduated scale or on the screen, in the case of a numerical scale, is a calculated value. The measurement of mass with this type of balance is an indirect measure. The only balance that weighs directly the mass is the balance with two equal wings, an ancient instrument, known by the Egyptians 5000 years ago.