THE gravity it is one of the four fundamental forces existing in nature. The other fundamental quantities are the electromagnetic interaction force, the weak force and the strong force. Simply put, gravity is the greatness responsible for defining the weight of a body, vertical and downward force that holds us together with the planet. Any object that moves in free fall is under the influence of the acceleration of gravity, which on Earth is equivalent to approximately 9.8 m/s2.
gravity on other planets
The gravity value depends on the mass and size of each planet., natural satellite, star etc. The table below shows the approximate value of the acceleration due to gravity for some celestial bodies.
mechanical definition
From the point of view of mechanics, gravity is the force of attraction that arises between two bodies simply by their presence at a point in space. THE Newton's law of universal gravitation determines that the gravitational force of attraction is directly proportional to the product of the masses and inversely proportional to the square of the distance separating the two bodies.
Fg = Gravitational interaction force (N);
G = Universal gravitation constant (G = 6.67 x 10 – 11 Nm2/kg2);
M = Largest body mass (kg);
m = Smallest body mass (kg);
d = Distance between bodies (m).
The weight of our bodies is the force with which we are attracted to the Earth. This force of attraction is mutual, that is, if we are attracted to the Earth, we also attract it. However, as the planet's mass is much greater than the bodies on it, this interaction is imperceptible.
Do not stop now... There's more after the advertising ;)
The value of the weight of a body depends on the acceleration of gravity to which it is submitted. According to the Newton's second law, weight can be defined as the product of the body's mass and gravity.
A body of 100 kg has a weight on Earth equal to 1000 N. If this body is placed on the Moon, its weight will be only 160 N, but the mass will be the same. Do not fool yourself! Changing planets or going to the Moon doesn't make anyone thin, as the mass of bodies is the same anywhere. The factor that changes is the force of attraction between the body and the planet.
modern definition
Studies carried out from the 20th century onwards are called Modern physics. the explanation of Albert Einstein for gravity it is related to the curvature generated in space due to the presence of a very massive body.
According to this theory, space and time are curved by the presence of a very massive body, and this generates the attraction we call gravity.
The video above demonstrates in a simple way the idea proposed by Einstein for gravity.
Zero gravity
The sensation of floating, as if there were no gravity, felt by an astronaut in space arises due to an “infinite” free-fall movement. Objects in space move around the Earth under the influence of their gravity, but with a horizontal velocity that gives them the sensation of perpetual falling. This feeling is called zero gravity.
By Joab Silas
Graduated in Physics
Would you like to reference this text in a school or academic work? Look:
JUNIOR, Joab Silas da Silva. "What is gravity?"; Brazil School. Available in: https://brasilescola.uol.com.br/o-que-e/fisica/o-que-e-gravidade.htm. Accessed on June 27, 2021.
What is Physics?
Click to learn more about black holes, small regions of space with gigantic masses, between tens and millions of times the mass of the Sun. Due to their great gravity, at a minimum distance, not even light can escape their great attraction, so it is impossible to see them directly.
