Calculate Surface Tension of Blood Plasma: Help Needed

In summary, to lift a wire ring of radius 2.07 cm from the surface of a container of blood plasma, a vertical force of 1.90×10-2 N greater than the weight of the ring is required. Calculate the surface tension of blood plasma from this information.
  • #1
lovelylm1980
18
0
can anyone help me out with this question:In order to lift a wire ring of radius 2.07 cm from the surface of a container of blood plasma, a vertical force of 1.90×10-2 N greater than the weight of the ring is required. Calculate the surface tension of blood plasma from this information.
I can't figure it out it seemed so easy at first but then i got the wrong answer.
 
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  • #2
Details? This looks like homework --- forum policy is that you show us your work, or state the difference between your answer and what is expected.
 
  • #3
surface tension is equal to force over length so what i though is that since the force and radiua are given that length L would be the radius times two and to get surface tension the force that is given would be divided by this number, but that's not right because it was the wrong answer.
 
  • #4
You got half the number expected?

Too late at night, I meant you got a surface tension "twice" what was expected.
 
Last edited:
  • #5
do you mean that i should take my answer and divide by two or multiply by two?
 
  • #6
Post your answer --- we'll go from there.
 
  • #7
surface tension= F/L
2.07 cm= .0207m
L= .0207m x 2= .0414m

1.90×10-2 N/ .0414m= .458 N/m
where do I go from here?
 
  • #8
Got bumped off for a minute --- Okay, now we get somewhere:
1) remember the formula for circumference of a circle? 2πr

2) when you're pulling the loop from the surface of the liquid, you noticed that the surface "draped" BOTH directions from the wire? Does it make sense to you that you're actually pulling against surface tension exerted against twice the circumference of the wire loop? Once around for the outside of the loop, and once more for the inside?

3) What I come up with on the back of the envelope, and I'm truncating --- you'll have to take it beyond the single significant digit, is 0.07 N/m.

I thought at first that you were hung up on just the trick of doubling the circumference of the loop for this type of measurement --- that's why I said "half" mistakenly, and corrected things to guess that you were getting "twice" the value you were expecting, but it's more like 6 times larger than what your answer key is looking for.

This work for you?
 
  • #9
Thanks alot! You really helped me Igot the answer of 0.0731 N/m, and it was right thanks again.
 

1. What is surface tension?

Surface tension is the measure of the force that holds the surface of a liquid together. It is the reason why some insects can walk on water and why droplets form on surfaces instead of spreading out.

2. Why is it important to calculate the surface tension of blood plasma?

The surface tension of blood plasma is an important factor in understanding the behavior of red blood cells and their ability to flow through blood vessels. It can also provide valuable information about the overall health and function of the body's circulatory system.

3. How is the surface tension of blood plasma calculated?

The surface tension of blood plasma can be calculated using the Law of Laplace, which takes into account the surface tension, radius, and pressure of the red blood cells. This equation can be solved using experimental data or through computer simulations.

4. What are some factors that can affect the surface tension of blood plasma?

The surface tension of blood plasma can be affected by various factors such as temperature, pH levels, and the presence of certain proteins or lipids. Certain diseases or medical conditions can also alter the surface tension of blood plasma.

5. How can the calculated surface tension of blood plasma be useful in the medical field?

Knowing the surface tension of blood plasma can help in diagnosing and monitoring certain medical conditions, such as pulmonary edema or certain types of anemia. It can also aid in the development of treatments and medications for these conditions.

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