Coalescence of Drops: Exploring Kinetic Energy & Star Formation

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In summary, the conversation discusses the process of coalescing drops and how the extra energy gained can give kinetic energy to the bigger drop. The factor that decides the velocity of the coalesced drop is the conservation of momentum. The conversation also touches on the comparison of this process with the p-p cycle of star formation and how the law of conservation of momentum is a robust principle in science. It is mentioned that an external force or torque is necessary to change the linear and angular momentum of the coalesced drop. The conversation concludes by questioning the stability of the bigger drop and the justification of this argument.
  • #1
gianeshwar
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Hello friends

Coalesced drops form a bigger drop and there is extra energy spare.Now this energy is said to give kinetic energy to bigger drop.Which factor decides the velocity of coalesced drop?
Is it just any accidental push after coalescence?
I think also that the process is just feasible with delta G of system negative .
Can I compare it with p-p cycle of star formation as well.
Question is scattered but I want to see the underlying processes and compare them.
Thanks!
 
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  • #2
For coalesced drops, the energy that is gained is from surface tension, because the surface area of the combined drops is less than the sum of the parts. The extra energy can go into heating of the drops rather than into any translational motion. For stars, I think the attraction can be a combination of gravitational and electrostatic, but I have little expertise in that area.
 
  • #3
Clearly, the added energy cannot go into bulk translational motion. Conservation of momentum dictates the final velocity of the merged drop.

The energy can go at least in part to oscillations in the droplet, for instance, an oscillation between an oblate spheroid and a prolate spheroid. It could also lead to the ejection of smaller droplets.
 
  • #4
Thank you friends!
Anyway why not a translational motion possible .Is it possible to consume extra energy in translational motion or even spin motion if there is any accidental negligibly small foce or torque to start.
 
  • #5
gianeshwar said:
Anyway why not a translational motion possible .Is it possible to consume extra energy in translational motion or even spin motion if there is any accidental negligibly small foce or torque to start.
Conservation of momentum and conservation of angular momentum will tell you how much linear velocity and how much spin results.
 
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  • #6
gianeshwar said:
Anyway why not a translational motion possible
The answer to this question is basically why no one has come up with a 'reactionless drive', despite many attempts and fake solutions. Sit in a box, in space and try to move (or change the velocity of) your (you + box) centre of mass by moving about inside the box. Whatever you do - running against the side and smashing into it etc. - will not change the total Momentum.
Of all the principles ('laws') of Science, the Conservation of Momentum Law seems to be the most robust. We have not yet found a single exception.
 
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  • #7
Thank you friends ! I understand that since coalesced drops had total linear momentum and total angular momentum zero so after coalescing there is neither any linear momentum nor any angular momentum of big drop.
Only an external force or torque or both could do so.
Similar things we can expect in star formation I think.
Delta G(Gibbs free energy) of this isolated system is negative I think .Bigger drop must be more stable.
Is my argument completely justified?
Thanks!
 

Q: What is the purpose of studying coalescence of drops?

The purpose of studying coalescence of drops is to understand the process of how smaller droplets merge together to form larger droplets. This process is important in many natural phenomena, such as rain formation and cloud formation, as well as in industrial processes such as oil extraction and inkjet printing.

Q: How does kinetic energy play a role in coalescence of drops?

Kinetic energy is the energy an object possesses due to its motion. In the coalescence of drops, kinetic energy is responsible for the movement and collision of smaller droplets, leading to their merger and formation of larger droplets. The amount of kinetic energy present in the system can affect the rate and outcome of the coalescence process.

Q: What factors can affect the coalescence process?

Aside from kinetic energy, other factors that can affect coalescence of drops include surface tension, viscosity, and droplet size and shape. Surface tension is the force that holds the surface of a liquid together and can either promote or inhibit coalescence. Viscosity, or the resistance of a fluid to flow, can also affect the rate of coalescence. Droplet size and shape can also play a role in how droplets merge, with larger or irregularly shaped droplets having a higher tendency to coalesce.

Q: Is coalescence of drops only relevant in the formation of stars?

No, coalescence of drops is not only relevant in the formation of stars. While it is a key process in star formation, it also plays a role in many other natural phenomena and industrial processes, as mentioned earlier. Understanding and studying coalescence of drops can have applications in various fields, from weather prediction to pharmaceuticals.

Q: How do scientists study coalescence of drops?

Scientists study coalescence of drops through experiments and simulations. In experiments, droplets of different sizes and compositions are observed and the coalescence process is recorded. In simulations, mathematical models are used to simulate the behavior of droplets and their coalescence. Both approaches allow scientists to study the process and understand the underlying mechanisms and factors involved in coalescence of drops.

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