Surface Tension (Conceptual Question)

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Homework Help Overview

The discussion revolves around the concept of surface tension, specifically how it relates to the ability of a needle to float on water without causing a depression in the surface. Participants are exploring the definition and implications of surface tension in a liquid medium.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants are questioning how surface tension supports the weight of a needle on water and whether the surface tension acts parallel to the surface without being perpendicular. There is also a query about whether the equation for surface tension considers the depression of the water surface.

Discussion Status

The discussion is ongoing, with participants seeking clarification on the relationship between surface tension and the behavior of water when a needle is placed on it. Some guidance has been offered regarding further research on the angle of contact, but no consensus has been reached.

Contextual Notes

There is a mention of potential confusion regarding the definition of surface tension and its practical implications, as well as the assumption that the water does not depress when a needle is placed on it.

SpringPhysics
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Homework Statement


(Sorry if this topic belongs to another forum.)

The definition of surface tension is the force exerted parallel to the surface of a liquid along a line of unit length, perpendicular to the line. So if, hypothetically, when you place a needle on the surface of water, the water does not depress, how is the needle's weight being supported at all? Would the surface tension be completely parallel to the surface of the water, but in no way perpendicular to the line?
 
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SpringPhysics said:

Homework Statement


(Sorry if this topic belongs to another forum.)

The definition of surface tension is the force exerted parallel to the surface of a liquid along a line of unit length, perpendicular to the line. So if, hypothetically, when you place a needle on the surface of water, the water does not depress, how is the needle's weight being supported at all? Would the surface tension be completely parallel to the surface of the water, but in no way perpendicular to the line?

The water does depress.
 
Dadface said:
The water does depress.

So the equation for surface tension takes into account that the water depresses?
 
SpringPhysics said:
So the equation for surface tension takes into account that the water depresses?

Yes,you may get more information if you google angle of contact.
 
Thanks.
 

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