What is hydrostatic equilibrium in physics?
In fluid mechanics, hydrostatic equilibrium (hydrostatic balance, hydrostasy) is the condition of a fluid or plastic solid at rest, which occurs when external forces, such as gravity, are balanced by a pressure-gradient force.
Is the moon in hydrostatic equilibrium?
The smallest body confirmed to be in hydrostatic equilibrium is the dwarf planet Ceres, which is icy, at 945 km, whereas the largest body known to not be in hydrostatic equilibrium is the Moon, which is rocky, at 3,474 km.
What is hydrostatic equilibrium shape?
The isotropic gravitational field compresses the star into the most compact shape possible. A rotating star in hydrostatic equilibrium is an oblate spheroid up to a certain (critical) angular velocity.
What is hydrostatic equilibrium in atmosphere?
behaviour of wind systems The atmosphere is mainly in hydrostatic balance, or equilibrium, between the upward-directed pressure gradient force and the downward-directed force of gravity. maintain the approximate geostrophic and hydrostatic balance, which are necessary for quasigeostrophic equilibrium.
How did Galileo invent the hydrostatic balance?
Galileo had some ideas for refining the practice and, at the age of 22, he wrote a little tract about it, which he entitled La Bilancetta, or “The Little Balance.” What Galileo described was an accurate balance for weighing things in air and water, in which the part of the arm on which the counter weight was hung was …
Is the sun in hydrostatic equilibrium?
Apart from some very tiny changes, the Sun is neither expanding nor contracting (it is in hydrostatic equilibrium) and puts out energy at a constant rate. Fusion of hydrogen occurs in the center of the Sun, and the energy generated is carried to the surface by radiation and then convection.
Is Miranda in hydrostatic equilibrium?
At just 470 km in diameter, Miranda is one of the smallest closely observed objects in the Solar System that might be in hydrostatic equilibrium (spherical under its own gravity).
What is hydrostatic equilibrium in geography?
Hydrostatic equilibrium is the distinguishing criterion between dwarf planets and small solar system bodies, and features in astrophysics and planetary geology. In addition to the Sun, there are a dozen or so equilibrium objects confirmed to exist in the Solar System.
What is a hydrostatic equilibrium?
This force balance is called a hydrostatic equilibrium. The fluid can be split into a large number of cuboid volume elements; by considering a single element, the action of the fluid can be derived. There are 3 forces: the force downwards onto the top of the cuboid from the pressure, P, of the fluid above it is, from the definition of pressure ,
What is hydrostatic balance in fluid mechanics?
In fluid mechanics, a fluid is said to be in hydrostatic equilibrium or hydrostatic balance when it is at rest, or when the flow velocity at each point is constant over time. This occurs when external forces such as gravity are balanced by a pressure-gradient force.
What is the hydrostatic equation for an atmosphere in equilibrium?
For an atmosphere in hydrostatic equilibrium, the balance of forces in the vertical requires that −δp = gρδz In the limit as δz → 0, ∂p ∂z = −gρ. This is the hydrostatic equation. The negative sign ensures that the pressure decreases with increasing height.
What happens when a volume of fluid is not in hydrostatic equilibrium?
When a volume of fluid is not in hydrostatic equilibrium it must contract if the gravitational force exceeds the pressure, or expand if the internal pressure is greater. A volume of fluid is in hydrostatic equilibrium when the downward force exerted by gravity is balanced by an upward force exerted by the pressure of the fluid.