We explain what equilibrium is in physics and its three different states. Also, the sense of balance and other uses of the term.
What is balance?
When we speak of equilibrium, in general, we refer to the state of a body in which the forces that act on it cancel or cancel each other, allowing it to remain in the same place or in the same shape, without moving or modifying.
This is an idea that we usually represent through the balance, that tool that we use to weigh objects. So much so, that the word itself comes from Latin equilibrium, formed by aequus, "Equal", and pound, "Balance".
Balances work by depositing the object to be weighed on one side and placing on the other certain counterweights whose weight is known, until both sides reach the same level, that is, until the balance does not tilt in any direction. This point is the point of balance, and any body or object of reality can experience it, as long as the forces acting on it cancel each other out, leaving it at rest.
There are, in this way, three different types of equilibrium state recognized by the physical, in which an object or a body can be found:
- Stable equilibrium, when the body or object resumes its position of stability once the forces acting on it have ceased, thus demonstrating a marked tendency towards equilibrium. For example, a pendulum that we push with the hand will move for a time, until the effect of the gravity always stop it at the same and exact resting point.
- Unstable equilibrium, when the body or object maintains a position of rest only while acting on it a certain force that compensates the others, so that, when said force ceases, the object loses its balance and moves to other places. For example, a pencil that we hold on its tip will fall in different directions when we release it, since its resting point depends on the strength of our hand.
- Indifferent equilibrium, when the body or object is capable of losing its resting position and reaching a new one spontaneously, without the need for new forces to act on it. This is what happens, for example, when placing a ball on a completely flat surface: it will not move in any direction, and if we push it a little, it will change position but will immediately regain its balance.
Sense of balance
We say that we have balance when we are able to move and carry out actions while staying upright, standing, although often in those cases we tend to move our arms, just like the plates of the balance, to keep the body in its center of gravity. .
Balanceception is the perception of the balance of the body. It is a physiological sense that we share with animals, whose function is to guide our body and prevent us from falling.
Thanks to it we can walk along a narrow railing and stand upright, or birds can perform pirouettes in the air and regain their flight position, or even beings as primitive as jellyfish can return to their "face up" position when they hit. turn around. All of these are ways of maintaining balance.
In the case of human being and from others mammals, this sense depends on the internal structures of the ear. It can be affected by diseases or infections that trigger dizziness, disorientation, and nausea.
Those same sensations can be elicited when someone stands on constantly moving objects, such as boats, airplanes, or roller coaster cars. Even astronauts have reported similar dizziness, as a result of prolonged exposure to weightlessness.
There are two different types of this body balance:
- Static equilibrium, when it refers to the ability to stay still and upright, without falling, on our feet or on just one, or on an object, etc.
- Dynamic balance, when it refers to the ability to stay upright and stable while doing other types of physical activities, such as walking on a tightrope or juggling on it, for example.
Other uses of the term equilibrium
In addition to those detailed so far, the word balance has other much more specific uses within certain fields of knowledge or disciplines, such as the following:
- Chemical balance. Term used in the chemistry to indicate that a chemical reaction reversible to reach a stable state, that is, when the substances they move between chemicals at the same rate, without producing a net change of any kind.
- Thermal equilibrium. Term from the field of physics, which refers to the state of two bodies in direct contact, whose temperatures initially different end up equating, as the heat it radiates in the direction of the hottest to the least hot, altering the temperature of both bodies.
- Ecological balance. Also called the balance of the nature, is a concept that proposes the state of equilibrium or homeostasis of biological systems, within which there is a tendency to preserve order: so many predators for so many prey, predating and reproducing at a fixed and orderly rate. A small modification within the system is corrected by the feedback negative of it. Instead, large and abrupt changes disrupt the balance and plunge the ecological system into chaos.
- Economic balance. This is the name given to the point of any productive economic system in which the demand for goods is identical to the supply, thus allowing prices to remain stable and in equilibrium, without the need for external forces to intervene in the productive circuit.