Understanding surface tension in liquids

Рет қаралды 806

3 ай бұрын

Here we discuss two different (but equivalent) ways of understanding surface tension in liquids, in terms of both forces and energy. We finish by explaining how surface tension causes liquid droplets to take on a spherical shape in the absence of external forces.
To support the channel: ko-fi.com/benyelverton
About me: I studied Physics at the University of Cambridge, then stayed on to get a PhD in Astronomy. During my PhD, I also spent four years teaching Physics undergraduates at the university. Now, I'm working as a private tutor, teaching Physics & Maths up to A Level standard.
My website: benyelverton.com/
#physics #mathematics #surfacetension #forces #energy #intermolecularforces #workdone #surfacearea #area #interface #liquid #fluid #particles #pressure #molecules #maths #math #science #education

Пікірлер: 11

@mingmiao364 3 ай бұрын

Thanks so much for taking my suggestion!!

@DrBenYelverton 3 ай бұрын

I've encountered a lot of sources that seem to suggest surface tension acts inwards so it was definitely worth making a video to clarify that it doesn't!

@mingmiao364 3 ай бұрын

@@DrBenYelverton Perhaps the authors of those sources mean the *net* force due to surface tension on a curved surface pointing inwards to explain surface area minimization? But ultimately this is due to attracting forces among molecules so in that sense the tangential components pointing outward

@alphadek 3 ай бұрын

Is it really necessarily attractive forces ? If the molecules are all identical, including their charge, shouldn't the force be repulsive ?

@DrBenYelverton 3 ай бұрын

@@alphadek The molecules are neutral overall, but they can still attract each other. Fluctuations in the charge density of the electron cloud around one molecule will cause that molecule to gain a temporary dipole moment. This will then induce dipole moments in other nearby molecules, and the molecules attract through dipole-dipole interactions.

@alphadek 3 ай бұрын

@@DrBenYelvertonok I get it !

@AmeerHamza-bc4fh Ай бұрын

So theoretically there should be a vertical reaction R on the surface element because of net downward inward forces of attraction. How that vertical R is not there and only the surface tension which is a horizontal force comes into the surface? I'm confused about this situation and my mind is not clear. Thanks for your reply.

@ayaan_maan Ай бұрын

Will you be making a series on properties of solids like elasticity, stress and strain? I really can't get my head around these concepts or the use of tensors in them (I tried reading Landau-Lifschitz but that got me nowhere).

@DrBenYelverton Ай бұрын

Will try to cover this some day, it's on my to-do list. I have never read the Landau & Lifshitz books but my impression is that they're probably not the best resource for gaining intuition!

@asharani759 3 ай бұрын

Imagine a person has compressed a massive spring with his finger and thumb, (let the total compression be x). Now the person releases the spring without any external jerk (Note that the spring has mass(M) and it is in air)... I am required to find the time in which the spring will be back in its natural length.. Sir cn u pls try to solve this question... my initial approach was finding the acceleration of topmost and bottomost points of spring, in order to find their respective displacements (wrt COM) (let be x1 and x2), thus to get back in natural length, x1+x2= x... But i am unable to draw FBD of points, and how do i consider their weight... If u have any other approach, or cn continue this method further, kindly tell. Thanks 😊

@DrBenYelverton 3 ай бұрын

That's an interesting question, I'll think about this and see if I can figure it out!