Tension Definition and 1000 Threads

Surface tension is the tendency of liquid surfaces at rest to shrink into the minimum surface area possible. Surface tension is what allows heavier than water i.e., denser than water objects such as razor blades, insects (e.g. water striders), to float and slide on a water surface without becoming even partly submerged.
At liquid–air interfaces, surface tension results from the greater attraction of liquid molecules to each other (due to cohesion) than to the molecules in the air (due to adhesion).There are two primary mechanisms in play. One is an inward force on the surface molecules causing the liquid to contract. Second is a tangential force parallel to the surface of the liquid. This tangential force (per unit length) is generally referred to as the surface tension. The net effect is the liquid behaves as if its surface were covered with a stretched elastic membrane. But this analogy must not be taken too far as the tension in an elastic membrane is dependent on the amount of deformation of the membrane while surface tension is an inherent property of the liquid–air or liquid–vapour interface.Because of the relatively high attraction of water molecules to each other through a web of hydrogen bonds, water has a higher surface tension (72.8 millinewtons (mN) per meter at 20 °C) than most other liquids. Surface tension is an important factor in the phenomenon of capillarity.
Surface tension has the dimension of force per unit length, or of energy per unit area. The two are equivalent, but when referring to energy per unit of area, it is common to use the term surface energy, which is a more general term in the sense that it applies also to solids.
In materials science, surface tension is used for either surface stress or surface energy.

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  1. C

    How do I calculate the Tension in a rope going over a smooth pulley?

    I really cant wrap my head around how I can find the tension i in the rope going from A to D via the smooth pulley B. P=4.91N Distances are in mm I assume I cant use the triangle EBD as it can be dynamic without the triangle ABC changing. I know I can find the y component of the tension in...
  2. danut

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    I'm struggling to get to the correct answer, which I posted down bellow. The pulleys are ideal, so I figured that m₁ and m₂ will both move upwards (towards the ceiling?) with the acceleration a, while m₃ will move downwards with the acceleration -a. Let T be the tension in the string which...
  3. Heisenberg7

    Tension Force Problem (applying Work-Kinetic Energy Theorem)

    We know that net work done is equal to the change in kinetic energy, so we write: $$\Delta K = W$$ The tension is acting at angle ##\theta## due to the x axis, so we will only be taking its x component ##T_x = T \cos{\theta}##. Since we can look at this as one dimensional motion (##T_y## does no...
  4. thejuanestevez

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  5. LarryS

    I Potential Energy in a Stretched String in SR

    In classical mechanics, the potential energy stored in an elastic stretched string is the work done by the tension during the stretching process. Is this concept and formula the same in Special Relativity? Thanks in advance.
  6. A

    B Rogowski coil tension calculation formula

    Hi everyone . I need help on the following problem. I built a current sensor that is based on the same principle as the Rogowski coil. Don't propose other alternative methods to measure the current because its application will be different and I don't want to talk about this. in reality what I...
  7. aiqing

    Is it friction or tension acting on the person hanging on a rope?

    The first question statement was under the chapter ##Newton's Laws Of Motion (Without Friction)##. Whereas, the second question was under ##Friction##. The free body diagram for the first question is given as: And the free body diagram for the other question is given as: In the first...
  8. T

    Block connected to 2 real pulleys

    For point one I analyzed all of the forces, called the tension on the right ##T_2## and the left one ##T_1##, and taking as positive the clock-wise and upwards directions I found: $$\begin{cases} T_2 - mg = ma \\ N_2= T_2 + M_2g + T_1 \\ N_1= M_1g - T_1 \\ τ_{T_2} - τ_{T_1} = I_2 α_2\\ τ_{T1} =...
  9. P

    Tension in a deformed cylindrical bag on a surface

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  10. Mordred

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  11. kirito

    I How is the net force on the system equal to 0 initially?

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  12. B

    Tension in a Two-Crate System on a Frictionless Surface

    for 4kg box: Fx = T m1a=T (4) (2.50) = T 10 = T for 6 kg box: Fx = Fa - T m2a = m2a - T 15 = 15 - T 15-15 = T 0 = T I assumed the tension would be the same for both boxes, they are supposed to be, so what did I do wrong and is the answer 10 or zero?
  13. chwala

    Find the tension in the rope PQ

    My interest is on part (a), the steps are clear. I thought the final solution ought to be ##T- 500 =50 ×0.2## ##T=500+10 = 510N## Unless I am missing something here, same query on part (b).
  14. kgehrels

    B Slack vs tight rope at the start of a pendulum

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  15. kgehrels

    Rope Swing, starting in tension vs slack

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  16. H

    What is the time taken by a pulse generated at the bottom of a string to reach the top?

    I have been taught that speed of pulse is v = √(T/μ), but here tension varies at each point therefore I cannot just simply apply the formula. I think integration would be needed, I tried but ended up nowhere. Can someone help me find the time?
  17. dcmf

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  18. daisy7777

    Uniform Circular Motion: Tension Force at Top of Circle

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  19. dcmf

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  20. chwala

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  21. I_Try_Math

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  22. I_Try_Math

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  23. S

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  24. Quantum Psi Inverted

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  25. I

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  26. Chrono G. Xay

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  27. J

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  28. P

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  29. H

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  30. Venturi365

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    The thing with this exercise is that I don't think that the question makes sense at all (or, at least, is incomplete). First of all, we don't know if the mass moves with any of those tensions, therefore I cannot know which coefficient apply. Second of all, even if we suppose that the mass is...
  31. Tesla In Person

    2 pullies and 3 masses -Tension

    Hi, If i have a system that consists of 2 pullies and 3 masses, what is the tension on each part of the string? I know that for 2 masses hanging on either side of a pulley, the tension is the same. But for 3 masses, and 2 ideal pullies(no friction) and inextensible string, is tension the same...
  32. yashboi123

    Tension in cable D is equivalent to the tension in cable B?

    I found the tension of cable B by doing mg + Csin(37.1). I found C by doing 757(Tension in cable A) = Ccos(37.1). I was just wondering if the tension in cable D is equivalent to the tension in cable B. If possible please show the steps on how you determined if they are equivalent or not. Thank you!
  33. JohnnyLaws

    Finding the angle that a string makes with a wall and its tension

    For a better understanding of this exercise here is the image illustrating the scenario described in the statement: So to solve this exercise I began by drawing a forces diagram: I believe I have explained everything in the "Relevant equations" section. What am I doing wrong? The book that...
  34. Say17

    Calculating Tension in a System of Trolleys

    Hi all, To find out the tension. First I have to find out the a. 1. step F = ma F = (m1+m2) *a F = (1+3)*a F = 4*a F/4 = a F = 10N + 50 N F = 60 N 60/4 = 15 m/s^2 2.step T =( m1/ (m1 + m2)) * F T = (1/ 1+3) * 60 T = 15 N But the final result is 20N. Thanks for your help!
  35. K

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  36. S

    Misc. Knot(s) to tie end of fishing line under tension

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  37. A

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    On question B, I've attempted a solution that I have posted. However, I don't think it's correct. Am I allowed to treat this rope that wraps around the rod as a "negative" force and simply attach it to the other side of the equation such that ## m_1g=m_2g+\mu_sN##?
  38. Mohmmad Maaitah

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    This is the problem and my answer below it. my friends said it's 250 N and I say it's 100 N based on what I solved what am I missing ?? my try:
  39. Justforthisquestion1

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    My Work so far: So there is a Force F applied to the right and since we have a no slipping condition we have a static friction force fs to the left. So the only thing that can move the center of mass (cm) of the yoyo is rotation. F would lead to a ccw rotation and fs to a clockwise rotation...
  40. P

    Tension in a spring that's bent into a semicircle

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  41. D

    Solving for Tension in Net Force Equation: Need Help!

    I have tried finding the tension of the string through the equation Net Force = T - mg = ma but I am struggling with coming up with the correct acceleration. Is my net force equation correct?
  42. C

    How does soap water membrane thickness affect surface tension?

    1.If the thickness of soap water surface decrease, whereas the concentration remain the same, how will the surface tension change? 2. If the membrane of soap water start to evaporate, its thickness become thinner and it’s concentration increase, How will the surface tension change? Thank you!
  43. chwala

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    This is an exam question - refreshing as usual. Literature Overview; In the free-body diagram shown above, we can see the horizontal and vertical components of the tension forces, T₁, and T₂. Forces are vectors, which means they always have both magnitudes and directions. Like all vectors...
  44. V

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    I would think that a force due to surface tension would act upwards on the plate and not downward, as shown in the diagram I have come up with. The surface of water would act as a stretched membrane and therefore there would be a surface tension on water surface in contact with the bottom of the...
  45. Spocktastic

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  46. M

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  47. samy4408

    I I found 2 formulas about surface tension -- which one is correct?

  48. samy4408

    Trying to understand alveolar surface tension

    Hello, I learned recently about alveolar surface tension, and the explanation provided in the course was not satisfactory, it said that it is due to the force that pushes water molecules of the outer layer to the inner layers, I don't understand why this force that pushes water toward the cell...
  49. M

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  50. babaliaris

    I Pendulum Tension Force -- How to calculate the full vector?

    Hello! I'm trying to understand how this pendulum works. I found this video that explains how to calculate the T force from the rope. He uses the preservation of kinetic and potential energy in order to find the magnitude of the velocity and then using Newton's second law, he calculates the T...
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