What is Tension: Definition and 1000 Discussions

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. Rikudo

    Tension between two rigid bodies

    Ok. So, I already worked on this problem, and get ##m_c## = 2m/3, which is correct according to the book. However, I also want to know the value of the tension (T) between rod A and B. Note: Before we start working on my modified question, I want to point out that the force exerted by the...
  2. A

    I My textbook is deriving wave speed on a string under tension

    My textbook is deriving wave speed on a string under tension with confusing thetas. It assumes ##\tan \theta_1 = \frac{-F_1}{F_T}## and ##\tan \theta_2 = \frac{F_2}{F_T}## which confuses me. I know for sure theta is the angle due to the position of y and x, ##\tan \theta = \frac{y}{x}##, but I...
  3. L

    I Surface tension and water (the smallest hole water will flow through)

    I am trying to find out what the smallest hole water will flow through. not a molecule of water, just water in general. Here is an example. I have a single walled cube that i 3d printed. When i put water in it, it leaks between the layer lines. I want to find out what the spacing between the...
  4. A

    Tension in string pulling two carts

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  5. kingofjong

    I Maximizing Compound Bow Power: The Role of Longer Limbs Explained

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  6. A

    I Understanding tension and centripedal force in a puck and weight

    For practice I did the following problem: Solving this problem mechanically was simple enough using the following force diagrams: Then $$F_{net_M} = T - Mg = 0$$ Due to the stationary condition $$T = mg$$ and $$F_{net_m} = T = ma_c$$ $$T = ma_c$$ Because centripedal acceleration is...
  7. rudransh verma

    B What is tension and how does it affect a rope?

    I have gathered everything from post “Monkey climbing up the rope” about tension. Tension is basically a force that the rope applies back when it is under stress. It is an inward force. Tension T's direction at end points of rope where its attached to the body and ceiling is inwards. Tension is...
  8. diogomcs

    I need an experiment about surface tension

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  9. runningphysics

    Two masses connected by a rope on a pulley on a ramp

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  10. Monsterboy

    Tension on both sides of the rope is supposed to be the same?

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  11. Cosmology2015

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  12. erensatik

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  13. Buzz Bloom

    I A relationship between flat vs. finite and (2) Hubble constant tension

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  14. S

    Finding the frequency of a string based on Mass and Tension

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  15. M

    Guitar string tension: effect of total length - continued

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  16. O

    Relationship between belt tension and pressure it exerts

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  17. HS21

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  18. paulsterx

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  19. kara123

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  20. R

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  21. Dario56

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  22. Dario56

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  23. mncyapntsi

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  24. B

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  25. Goinger

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  26. timotola

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  27. T

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  28. T

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  29. Shreya

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  30. P

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  31. adammish

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  32. S

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  33. D

    Is Fgy the Same as FN in a System with Two Masses and Friction?

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  34. E

    What is the tension of the rope?

    I have attached two different attempts to solve this problem. They both look correct to me but they give two different answers! Which one is correct, which one is wrong and why?
  35. M

    Tension and compression forces on a femur bone

    Summary:: Hello all, I need help with this question, ill attach the equations i managed to solve. How do i continue from there?
  36. Hamiltonian

    Tension developed in a charged ring

    consider a small element that subtends an angle ##2\Delta \theta## at the center of the ring. balancing the forces on this element gives: (let the field due to the ring be at its circumference be ##E##). $$2T\Delta \theta = E(dq) = E (\frac{Q}{2\pi})(2\Delta \theta)$$ $$T = \frac{EQ}{2\pi}$$ now...
  37. P

    Problem on Pressure due to Surface tension

    The method to solving this is to equate forces along a portion of the balloon through which ##\sigma_L## acts, and another portion through which ##\sigma_t## acts. The former potion should be a circular cross section of the cylinder, while the latter will be a rectangular cross section. You will...
  38. J

    Finding the tension of a support cable to balance the beam

    I know the answer is 170 but I am not sure how to get there. I tried doing things backwards g=9.8 t = fr = mgr 0= 170 + tbl - tbr - 5x9.8x1.5 0= 170 + tbl - tbr - 73.5 -96.5 = tbl - tbr -96.5 = 18*9.8 * 0.2 - 18*9.8*1.4 -96.5 does not equal -211.68
  39. P

    Good resources for learning basic surface tension

    Summary:: Hi, I realized that surface tension is not covered in introductory physics textbooks. Where can I get a good introduction on surface tension? *info provided should be about the same depth as topics in Halliday, Young. Hi, I realized that surface tension is not covered in...
  40. R

    Variation of the Speed of Sound in metals under tension

    In a block of metal, each metal has a characteristic speed of sound. When metal is under tension, such as a guitar string, the speed rises as the tension increases. How does the speed vary (in a block say) as a function of tension along each of the three axes? I am assuming that transverse...
  41. Chestermiller

    Time Average Value of Pendulum String Tension

    Another member and I, in private conversations, have been discussing the time average tension in a pendulum string. He has done a numerical analysis of the problem, and his calculations indicate that the time average tension is less than mg. I have analyzed the problem analytically by...
  42. J

    Solve T(y)-T(y+dy)=ug(dy) | Easier Method?

    T(y)-T(y+dy)=ug(dy) is what I have got. How would I solve this? Or is there a simpler method.
  43. H

    Engineering Tension force in two strings supporting a sign

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  44. F

    Tension in rope for non-uniform circular motion with air resistance

    I'm trying to solve this problem using an rtz coordinate system, and Newtons second law. I know that mar = (m(v)2)/r. I'm failing to understand how mg and the drag force affects the solution and how I would set it up. I know if it was at the bottom of the circle that mg would be added to the...
  45. J

    Waves -- How does increasing tension affect frequency and period?

    Using this stimulation: https://phet.colorado.edu/sims/html/wave-on-a-string/latest/wave-on-a-string_en.html It looks like frequency is decreasing as I increase tension but online it says frequency increases as tension does. Also, I am unsure about what happens to the Period
  46. P

    If I pull a pulley, what is the tension in the string around it?

    I assumed that each of the masses attached to the string would be pulled with a force F, instead of F/2, which appears to be the correct value. Why is it F/2? I suspect the fact that the pulley is "weightless" has something to do with the F/2 value. What is it? Thank you.
  47. B

    Find the tension in the wire from this mass hanging at an angle

    I do not understand how this type of exercise is solved because I have not had a solution to such an example. I would ask you to show me the solution of this exercise step by step, so that I understand how to solve it. I appreciate your help. Thank you.
  48. K

    Finding the torque required for telescopic cable mechanism

    Summary:: I am designing a linear telescopic system that gets elevated with a step motor, but in order to find the compatible motor, I need to work out the torque that is required for the elevation. I have uploaded my CAD model to this thread with how cables are connected. Could someone please...
  49. A

    Calculating the surface tension using the method of Lecomt de Nouy

    Hello! I am having unexpected difficulties with this problem.A friend showed me an article regarding the Lecomde ring method,and at the bottom was this little problem that to solve.I've done it like this. $$ y = \frac{F}{4\pi r} $$ where F is the given force and r is = 0,0325 in meters. The...
  50. I

    Difference in tension introduced by friction

    I have no clue how to do this, so I did my best guess of it. Friction is μN, N being the normal force. The normal force when it is in contract with the pole should be V2/R, R being the radius of the pole. So ΔT = μV2/R The answer provided is μTΔθ
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