Tatiane: "What is your weight?"
Paola: "I weigh 47 kg."
This type of dialogue is common in everyday life, but are Tatiane and Paola correctly relating the value of 47 kilograms to the Weight?
Although we understand that they refer to the amount of matter in Paola's body measured on a scale, they are wrong when they say that this value is the Weight. In fact, they make a reference to the pasta of Paola. What is the difference between these quantities?
→ Mass
THE pasta it is “the amount of matter present in a body and measured on a scale”. At the International System of Units, the default unit chosen since 1960 for the pasta is the kilogram (kg).
The standard kilogram is equivalent to a cylinder 3.917 cm in height and diameter. This cylinder was made from 10% iridium and 90% platinum and is housed inside three glass domes at Bureau headquarters. International Weights and Measures, in the city of Sèvre, France (the image below is a little older, so it has only two domes). It is triple insulated to prevent oxygen and moisture in the air from deteriorating these metals and affecting their precise mass.
The standard kilogram cylinder is used for comparison. In the case of Paola, for example, her mass is equal to 47 times the mass of a kilogram. All bodies have mass, no matter where they are. Paola has a mass of 47 kg on Earth, the Moon, Mars or even if she was isolated from any body.
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→ Weight
O Weight, in turn, can be calculated by multiplying the mass of the body and the acceleration of local gravity:
P = mg
NOTE: The standard SI weight unit is the Newton (1 N = 1 kg. m/s2).
O Weight depends on the attraction that one body exerts on the other, which is determined by the gravity acceleration. The greater the mass of the body, the greater this attraction. The Earth's mass (5.97. 1024 kg) is much larger than the mass of the Moon (7.4. 1022 kg), so a person's body is more attracted to the surface of the Earth than to the surface of the Moon. In other words, the acceleration of gravity on Earth is greater, and this affects the weight of the body attracted to it.
Paola's weight is one on Earth, one on the Moon, and one on Mars. If Paola is isolated, that is, if she is not close to any other body, she will have no weight.
By Jennifer Fogaça
Graduated in Chemistry
Would you like to reference this text in a school or academic work? Look:
FOGAÇA, Jennifer Rocha Vargas. "Difference between mass and weight"; Brazil School. Available in: https://brasilescola.uol.com.br/quimica/diferenca-entre-massa-peso.htm. Accessed on June 27, 2021.
