Gravitational Collapse: Internal Energy & Potential Energy

In summary, during gravitational collapse, the conversion of gravitational potential energy into internal kinetic energy leads to an increase in the internal energy of the gas. However, the thermodynamic definition of internal energy does not typically include gravitational potential energy. This means that the conversion of one form of internal energy into another is necessary to sustain the collapse. Additionally, in order to maintain the collapse, there must be a decrease in the system's total energy, which can be achieved through heat loss or work exchange.
  • #1
mystreet123
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During gravitational collapse, gravitational potential energy of the gas is converted to its internal kinetic energy so the internal energy of the clous of gas is said to be increased

But isn't gravitational potential energy included in the internal energy? Shouldn't the internal energy remains constant overall?
 
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Welcome to PF;
"Internal energy", in this context, refers to the thermodynamic definition.
This does not usually include gravitational potential energy.
You can see this, if you like, as one form of internal energy turning into another form.

Total energy is conserved - internal energy does not have to be conserved.
For instance, the object could undergo some nuclear reactions increasing internal energy or the object could radiate, decreasing internal energy.
 
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  • #3
Simon Bridge said:
"Internal energy", in this context, refers to the thermodynamic definition.
This does not usually include gravitational potential energy.
You can see this, if you like, as one form of internal energy turning into another form.

Total energy is conserved - internal energy does not have to be conserved.
For instance, the object could undergo some nuclear reactions increasing internal energy or the object could radiate, decreasing internal energy.
Thanks Simon

not my field of expertise ... was interested in hearing an answer as well :smile:

D
 
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Another interesting point about gravitational collapse is that to keep it going, it generally does require a decrease in the system total energy ("internal" energy plus potential energy). Whenever gravitational energy is converted 100% into internal energy, it will eventually stop the collapse, so you need some heat loss from the system to keep it going. But it takes relatively little heat loss if the gas is relativistic, so that's why gravitational collapse happens for relativistic gases.
 
  • #5
mystreet123 said:
But isn't gravitational potential energy included in the internal energy?

Yes, but only if it is no potential energy in an external field.

mystreet123 said:
Shouldn't the internal energy remains constant overall?

Yes, but only if no heat or work is exchanged over the system boundaries.
 

Related to Gravitational Collapse: Internal Energy & Potential Energy

1. What is gravitational collapse?

Gravitational collapse is the process by which a massive object, such as a star, collapses in on itself due to its own gravity. This can happen when the internal pressure of the object is no longer strong enough to counteract the force of gravity.

2. How does internal energy play a role in gravitational collapse?

Internal energy is the energy contained within a system, such as the heat and motion of particles. In the case of gravitational collapse, the internal energy of a massive object is what creates the pressure that keeps it from collapsing. As the object loses internal energy, its pressure decreases and it becomes more susceptible to gravitational collapse.

3. What is potential energy in relation to gravitational collapse?

Potential energy is the energy an object possesses due to its position or shape. In the case of gravitational collapse, the potential energy of a massive object is what allows it to collapse in on itself. As the object collapses, its potential energy is converted into kinetic energy, causing it to become more compact and dense.

4. Can gravitational collapse lead to the formation of a black hole?

Yes, gravitational collapse can indeed lead to the formation of a black hole. When a massive object collapses, it can reach a point of infinite density and zero volume known as the singularity. This singularity creates an intense gravitational pull that even light cannot escape from, resulting in a black hole.

5. Is gravitational collapse a common occurrence in the universe?

Gravitational collapse is a natural and common occurrence in the universe. It is responsible for the formation of stars, galaxies, and even larger structures such as galaxy clusters. It is also a key process in the life cycle of stars, as they eventually collapse and die, releasing their elements back into the universe.

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