Surface Tension (Conceptual Question)

In summary, the definition of surface tension involves the force exerted parallel to the surface of a liquid along a line of unit length, perpendicular to the line. When placing a needle on the surface of water, the water does depress and the surface tension is both parallel and perpendicular to the surface of the water. The equation for surface tension takes into account the depression of water and further information can be found by searching for the angle of contact.
  • #1
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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  • #2
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.
 
  • #3
Dadface said:
The water does depress.

So the equation for surface tension takes into account that the water depresses?
 
  • #4
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.
 
  • #5
Thanks.
 

What is surface tension?

Surface tension is a property of liquids that causes the surface of the liquid to behave like a stretched elastic membrane. It is the result of the cohesive forces between molecules at the surface of the liquid.

How does surface tension work?

Surface tension is caused by the unbalanced cohesive forces between molecules at the surface of a liquid. These forces pull the molecules at the surface closer together, creating a "skin" on the surface of the liquid.

What factors affect surface tension?

The surface tension of a liquid is affected by the type of liquid, temperature, and any substances dissolved in the liquid. Generally, surface tension increases with stronger cohesive forces between molecules.

What are some real-world examples of surface tension?

Surface tension can be seen in the way water droplets form on surfaces, the way insects can walk on water, and the way water forms a curved meniscus in a graduated cylinder. It also plays a role in the functioning of our lungs and alveoli.

How is surface tension measured?

Surface tension can be measured using a device called a tensiometer, which measures the force required to pull a thin wire out of the liquid's surface. It is typically measured in units of force per unit length, such as dynes per centimeter.

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