Surface Tension: Calculation & Unit Conversion

In summary, the conversation discusses a physics assignment on the relationship between surface tension and temperature. The formula for surface tension is given and the speaker has calculated the surface tension at various temperatures using a capillary tube and measuring the height. However, they are unsure of the units, with measurements in g/mm^2, mm, and mm/s. They question whether the answer will be in dyns/cm or ergs/cm^2 and express gratitude for the help. It is clarified that surface tension is force/length and the speaker hopes to receive a good grade on their assignment.
  • #1
shamstar
10
0
i am doing a physics assignment on the realationship between surface tension and temperature. i have calculated the surface tension at various temperatures using a capillary tube and measuring the height. i was given the formula:
surface tension=(densityxradius of tubeheight of columnxgravity)/ 2
i have calculated the surface tension, however, I am not sure what units it is in. density was measured in g/mm^2, radius and height were measured in mm, gravity was measured in mm/s. I am not sure if the answer will be dyns/cm or ergs/cm^2? or even something else? thankyou
 
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  • #2
shamstar said:
i am doing a physics assignment on the realationship between surface tension and temperature. i have calculated the surface tension at various temperatures using a capillary tube and measuring the height. i was given the formula:
surface tension=(densityxradius of tubeheight of columnxgravity)/ 2
i have calculated the surface tension, however, I am not sure what units it is in. density was measured in g/mm^2, radius and height were measured in mm, gravity was measured in mm/s. I am not sure if the answer will be dyns/cm or ergs/cm^2? or even something else? thankyou

First of all convert all the mm reading to cm. Also measure the density in gms per cm^2 and g as cm/s^2. Now you will get in dynes/cm.
 
  • #3
surface tension=force*length.

[tex]f=MLT^{-2}[/tex]
Hence surface tension=[tex]ML^2T^{-2}[/tex]
 
  • #4
chaoseverlasting said:
surface tension=force*length.

[tex]f=MLT^{-2}[/tex]
Hence surface tension=[tex]ML^2T^{-2}[/tex]

I think that you have made some mistake. Surface tension is force/length.It is torque which is force*length(radius). So surface tension would be ML^0T^-2
 
  • #5
thanyou both so much. let's hope a get an A on my assignment! thanks again
 

1. What is surface tension?

Surface tension is a physical property of liquids that describes the force exerted on the surface of a liquid due to the cohesive forces between the molecules of the liquid. It is the force that causes the surface of a liquid to behave like a stretched elastic membrane.

2. How is surface tension calculated?

Surface tension is calculated by dividing the force acting perpendicular to a line on the surface of a liquid by the length of that line. Mathematically, it is represented as surface tension (γ) = force (F) / length (L).

3. What are the units of surface tension?

The SI unit for surface tension is Newtons per meter (N/m). However, it can also be expressed in other units such as dynes per centimeter (dyn/cm) or millinewtons per meter (mN/m).

4. How is surface tension measured?

Surface tension can be measured using a variety of methods such as the du Noüy ring method, the Wilhelmy plate method, or the capillary rise method. These methods involve measuring the force or deformation of a liquid's surface due to surface tension.

5. How does temperature affect surface tension?

Surface tension decreases as temperature increases. This is because as temperature increases, the kinetic energy of the molecules in the liquid also increases, causing them to move more freely and reducing the cohesive forces between them. As a result, the surface tension decreases.

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