The Pressure Excess Notion: Why is the Formula Multiplied by 2?

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SUMMARY

The discussion clarifies the pressure excess notion in fluid mechanics, specifically addressing the formulas for pressure in water droplets and bubbles. For a full droplet of water, the pressure is calculated using the formula p = 2T/r, where T represents surface tension and r is the radius. In contrast, for a bubble, the pressure is given by p = 4T/r due to the presence of two surfaces—internal and external. This distinction is crucial for understanding the behavior of fluids in different geometries.

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  • Understanding of fluid mechanics principles
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in the surface tension about the pressure excess notion i have problem: why for a full dropplet of water the formula is p=2T/r whereas for a bubble p=4T/r. Why does it be multiplied by 2.
 
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In a filled drop there is only a surface. In a bubble there is also the internal surface. When you increase the radius, in the first cas,e only a surface increases. In the second, two surfaces increase.
 
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