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samy4408
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I found 2 formulas about surface tension -- which one is correct?
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In summary, the formulas for surface tension were derived by searching on Google and considering the use of a solid disk and thin ring floating in a fluid. The surface tension force can be imagined as a uniform distribution of tiny parallel springs, with the ring requiring half the spring constant of the disk due to its longer interface.
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Can you provide the context or references of how these formulas were derived?
- #3
samy4408
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I found the first one by typing surface tension formula on google , and the second :kuruman said:
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Which you use depends on what question you wish to answer. Say you have a solid disk and a very thin ring both of circumference ##C## and weight ##W## floating in a fluid. In the case of the disk, ##\gamma_{\text{disk}}=\dfrac{W}{C}##; in the case of the ring, ##\gamma_{\text{ring}}=\dfrac{W}{2C}.##
You can imagine the surface tension force as the resultant of a uniform distribution of tiny parallel springs around the length of the interface of the object and the fluid with ##\gamma## playing the role of the spring constant. The ring has twice as long an interface (on the inside and outside) as the disk and therefore twice as many springs. Thus, half the spring constant is required to support the same weight.
You can imagine the surface tension force as the resultant of a uniform distribution of tiny parallel springs around the length of the interface of the object and the fluid with ##\gamma## playing the role of the spring constant. The ring has twice as long an interface (on the inside and outside) as the disk and therefore twice as many springs. Thus, half the spring constant is required to support the same weight.
1. What is surface tension?
Surface tension is the measure of the force that is required to stretch or break the surface of a liquid. It is caused by the cohesive forces between the molecules of the liquid.
2. How is surface tension measured?
Surface tension is typically measured in units of force per unit length, such as newtons per meter (N/m) or dynes per centimeter (dyn/cm). It can be measured using various methods, including the drop weight method, capillary rise method, and Wilhelmy plate method.
3. What are the 2 formulas for surface tension?
The two most commonly used formulas for surface tension are the Young-Laplace equation and the Gibbs equation. The Young-Laplace equation relates surface tension to the curvature of a liquid interface, while the Gibbs equation relates surface tension to the interfacial energy between two phases.
4. Can both formulas for surface tension be correct?
Yes, both formulas can be correct depending on the specific scenario and conditions being studied. Each formula has its own assumptions and limitations, so it is important to use the appropriate formula for the given situation.
5. How do I determine which formula to use?
The formula to use for surface tension calculations depends on the specific system being studied and the information that is available. It is important to consider factors such as the type of interface, the shape of the interface, and the properties of the liquid and surrounding environment when selecting the appropriate formula.
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