Formula of weight of surface water

In summary, the weight of water at the water surface is given by the formula 2(pi)Rσ(cos angle), where R is the radius of the capillary tube, σ is the surface tension, and phi is the angle of contact between the water surface and the capillary. This formula takes into account the force of surface tension acting over the length of contact between the water surface and the capillary.
  • #1
goldfish9776
310
1

Homework Statement


Why the weight of water at water surface is given by formula 2(pi)Rσ(cos angle) ?

Homework Equations

The Attempt at a Solution

 

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  • #2
Is there more context to this?
My guess is that a capillary tube has been inserted into water reservoir, resulting in a column of water rising height h (compared with the water remaining in the reservoir). The weight of this column is held up by surface tension in the meniscus. Phi will be the angle of contact of the meniscus.
 
  • #3
haruspex said:
Is there more context to this?
My guess is that a capillary tube has been inserted into water reservoir, resulting in a column of water rising height h (compared with the water remaining in the reservoir). The weight of this column is held up by surface tension in the meniscus. Phi will be the angle of contact of the meniscus.
how about 2(pi)R ? how it comes?
 
  • #4
goldfish9776 said:
how about 2(pi)R ? how it comes?
Surface tension is a force per unit length. What is the length of contact between the water surface and the capillary (radius R)?
 

1. What is the formula for calculating the weight of surface water?

The formula for calculating the weight of surface water is W = V x D, where W is the weight in pounds, V is the volume in cubic feet, and D is the density in pounds per cubic foot.

2. How do you determine the volume of surface water?

The volume of surface water can be determined by multiplying the surface area of the water (in square feet) by the average depth of the water (in feet).

3. What is the density of surface water?

The density of surface water varies depending on factors such as temperature and salinity. However, the average density of freshwater is 62.4 pounds per cubic foot.

4. Can the formula be used for any body of water?

Yes, the formula for calculating the weight of surface water can be used for any body of water, as long as the volume and density are known.

5. Why is it important to know the weight of surface water?

Knowing the weight of surface water is important for various reasons, such as determining the amount of pressure on structures built on or near water, understanding the impact of water on the environment, and calculating the weight of objects floating on the water's surface.

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