The ‘Brownian ratchet’ and its relevance to the second law of thermodynamics.

In summary, the reason the Brownian ratchet fails to negate the second law is due to the interaction between the molecules in the second chamber and the 'pawl', similar to the interaction with the paddle wheel. However, if the temperature in the first chamber is higher than the second, it can produce useful work while still complying with the laws. This can be explained by the ratchet acting as a heat engine. In the case of a vacuum in the second chamber, the failure to extract useful work can still be explained by the temperature comparison, but it would seem to allow for the extraction of work from the first chamber. Further clarification on this topic would be appreciated.
  • #1
YoshiBeans
8
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My question is regarding the reason why the Brownian ratchet fails to negate the second law.

The explanation that I have been told relates to the fact that the molecules in the second chamber would interact with the 'pawl' in a similar manner to those interacting with the paddle wheel, negating the overall useful rotation.

I have also been told that if T1 is higher than T2, then it will produce useful work, but that this complies with the laws by acting like a heat engine.

My question is: How can the same failure to extract useful work be explained if there was a vacuum in the second chamber? This would negate the temperature comparison, and would seem to allow the extraction of work from the first chamber.

I would appreciate any available illumination. Thank you.
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  • #2
I would really like to know this too.
 

1. What is the Brownian ratchet?

The Brownian ratchet is a theoretical device that uses the random motion of particles, known as Brownian motion, to extract useful work without any external energy input.

2. How does the Brownian ratchet relate to the second law of thermodynamics?

The Brownian ratchet is often used as an example to explain the second law of thermodynamics, which states that the total entropy (disorder) of a closed system will always tend to increase over time. The ratchet appears to violate this law by seemingly creating order from disorder, but in reality, it does not as it relies on the input of external energy to function.

3. Can the Brownian ratchet be used to create perpetual motion or free energy?

No, the Brownian ratchet cannot be used to create perpetual motion or free energy. It only appears to do so because it relies on an external energy source to function, which ultimately increases the overall entropy of the system.

4. Is the Brownian ratchet a physical or theoretical device?

The Brownian ratchet is a theoretical device that has not been physically built or observed. It is used as a thought experiment to demonstrate principles of thermodynamics and does not have any practical applications.

5. Are there any real-life examples of the Brownian ratchet?

While the Brownian ratchet has not been physically built, there are some biological systems that exhibit similar principles. For example, certain proteins in cells use Brownian motion to move along cellular structures and perform specific tasks, such as transport and movement.

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