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Hydrostatic equilibrium occurs when compression, due to gravity, is balanced by a pressure gradient, which creates a force in the opposite direction. In stars, the pressure gradient appears as a result of the huge quantity of thermal energy (which acts outward) created by nuclear fusion reactions. It is gravity and this thermal energy that are in equilibrium.
It's a bit like blowing a balloon up, the inward pressure is counteracted by the external pressure of the atmosphere. In addition, when we consider stars, this means that the larger the mass of the star, the higher the temperature must be to achieve this balance. Larger stars will use up their supply of hydrogen more quickly and live a shorter life.
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What are the two forces that are equilibrium in a star?
Hydrostatic and Equilibrium
How is hydrostatic equilibrium in a star determined by its mass?
Hydrostatic equilibrium has nothing to do with the mass of the star but the compression, due to gravity, balanced by pressure of the star.See the related question.
The maintenance of hydrostatic equilibrium of the Earth's crust is called?
isostasy
What is a hydrostatic equilibrium?
Stars are held together by gravity and internal pressure that keeps them from collapsing. Gravitational attraction balances the internal pressures when this happens hydrostatic equilibrium is reached. In stars like the sun, gravity wants to crush the star but pressure from fusion pushes out. Gravity and fusion then equal out and hydrostatic equilibrium is achieved.
What are the two forces producing hydrostatic equilibrium in the sun?
electrical forces and gravity
What process allows the sun to stay the same size?
Hydrostatic and thermal equilibrium
Is Pluto in hydrostatic equilibrium?
Yes, Pluto has been determined to be in hydrostatic equilibrium. Planets must orbit the sun (the first criterion for a planet), and must also be in hydrostatic equilibrium (which Pluto is). Pluto fails the third "planetary entrance test" set by the IAU in that it has not cleared its orbit of debris. A link can be found below to check facts and learn more.
Why is Mars round?
Basically it is because of gravity. The technical explanation is called the " principle of hydrostatic equilibrium ".
A balance between the weight of a layer in a star and the internal energy pressure that supports it is?
hydrostatic equilibrium
How does the sun maintain its size and shape for over 5 billion years?
Hydrostatic equilibrium. See related question.
Why doesnt the sun collapse?
Because the temperature of the core keeps the Sun in hydrostatic equilibrium. See related question.
Why is Mimas not considered to be in hydrostatic equilibrium?
I think it is. Take a look at some pictures of Mimas; it looks pretty round to me.
