Surface Tension of Water, Capillary Action, Cohesive and Adhesive Forces - Work & Potential Energy

This physics video tutorial provides a basic introduction into the surface tension of water. Surface tension prevents small amounts of water from flattening out across a surface. Rather, it causes water to minimize its surface area and as a result, water forms small beadlike droplets. This video also discusses the capillary action of water as it is draw up through small tubes known as capillaries. Surface tension can be calculated by divided the force per unit length required to increase the area of a fluid. The surface tension opposes the force and attempts to minimize the area. The work required to increase the area of a fluid by a force is the surface tension multiplied by the increase in area. This video discusses the difference in the capillary effects between water and mercury. Water rises above the surrounding fluid level in a thin glass tube where as mercury descends below that line. The adhesive forces in water is greater than the cohesive forces. In Mercury, the cohesive forces are greater than the adhesive forces. Adhesive forces exist between different molecules and atoms. Cohesive forces exist between the same type of molecules and atoms.
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[@TheOrganicChemistryTutor]

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[@ahmedasmail9866]

Is this given area wire the area of ​​one face or is it the area of ​​both sides? Because if it is the area of ​​one face, we must multiply it by 2, but if this is the area of ​​both sides, then we put it as it is.

[@ahmedasmail9866]

Is this given area wire the area of ​​one face or is it the area of ​​both sides? Because if it is the area of ​​one face, we must multiply it by 2, but if this is the area of ​​both sides, then we put it as it is.

[@augijyotbali2131]

Do a face reveal video , wanna see who this genius is !!

[@undefined.infinity3106]

agree

[@carpediemvd]

Agree

[@Kiran-ye7ix]

Peter Parker

[@Photo_doctor]

Your face is more beautiful

[@maeyamisinapily]

Desperate punk get lost with your lustness no bad energy is needed ...

[@MichaelHoughton22]

Who also loves it when he says " Lets go ahead and finish this problem"?

[@marlonsebastian4986]

I just want you to know that You have a huge part in my college life. Thank you for that

[@purpleparadise2001]

Please create a separate playlist for fluid dynamics

[@Shampoo2004]

You are a gift from god
Im in uni now and i still watch your videos

[@adityaadit2004]

I still don't get it why y = F/2L ??? Why force is divided by 2? or why length is multiplied by 2?

[@LTDeskyPOP1]

if u found out lmk

[@mintallyunstable]

because there are 2 surfaces; front and back. think of a soapy water film when you blow bubbles.

[@mintallyunstable]

​​@@LTDeskyPOP1 check my reply

[@fredkester6130]

thank you for a very good question and for the answer

[@KitsoMolamodi-lx9zw]

For the 2L you will be basically looking for the perimeter of the needle ,from what we know a needle has 2 lengths and 2widths for the widths its just an assumption 😂 is not included cause it's soo small we can't measure it there so we gonna say 2l for the lengths

[@kealebogantlwana2316]

The day I graduate you will be the first person I recognize😁you are truly a god-sent

[@futoriousentertainment2956]

You forgot the factor of two when calculating the work required. It is W = 2γA, but you have used W = γA.

[@shankylezapanta1464]

yes he did

[@fredkester6130]

thank you, I was thinking I missed something

[@hqs9585]

Why did you not use the 1/2 on the second part of the problem for surface tension (Gamma = F/2L)

[@muhammedlawal3726]

I also don’t get it

[@trinaeset]

Yo my physics teacher gives me a chance to fix my grade by downloading a video on a certain subject and i i download most of your videos. Thanks

[@augijyotbali2131]

You deserve much subscriptions

[@ajmcorlean2913]

Hello Mr Tutor
Am really appreciative for all your work... i love it.....
But if yiu could only show me how to derive formula of capillary rise, and also derivation of volume from a venturimeter

[@ranaabazer]

I loved when he said now we will take about iam very excited

[@fuhrmanator00]

Why is each tube drawn with the bottom open but the top closed? A tube is open on both ends, right? I fear some people will be confused because of that.

[@get_going34]

U are the godddd.....
Thank you man for the video!! :)

[@johnnybuoy9551]

4:54 I did not get it, why we put 2 in the denominator of the equation

[@clintonxiggy6054]

Solve questions on capillarity and Angle of contact

[@acruzp]

Your accent is so cool

[@kinanaabueideh2315]

you are the best, thank you.

[@zeb_on_air]

Excuse me, I don't understand why the force applied to produce this work must be euqal to y*2L . In this way, wouldn't the movable bar remain fixed in its position? I mean, how are we supposed to "stretch" the surface of the liquid with a force that is equal to the upward pulling?

[@shroukesam6299]

me neither? also how in the start of the video we said that surface tension tends to make the surface area smaller then when we came to the solving of the problem we said surface area is the work required to increase the area ?

[@dhruvamudaliar6373]

Very helpful video

[@mabrukamaina7046]

thanks so much. It helped a lot! :)

[@williamsemmanuel3938]

Amazing tutorial video 📸

[@saraalde_7]

هذا ضروري يسلم ابي ادعي له بالجنة

[@linma1130]

I saw paper saying surface tension force parallel to the surface of liquid, while many information from the Internet says it is vertical to the surface and directed to the inside of the liquid. It is confused me.

[@yanbingzhu4650]

I don’t understand why we have to deal with the length in front and behind the rod.

[@hqs9585]

agree, me neither

[@hqs9585]

One way to understand this is this: the wire is contacting the reservoir in a rectangular manner, but in a thin wire the perimeter is simply the length times two, we can neglect the width in that case. So the actual force is along two side of the wire (not really SIDES but the wire (round) touching a flat surface makes it a line of intersection) . Hope this helps. so force total need the whole length. I am afraid his explanation is wrong and so is the use of 1/2

[@hanaa7668]

The best

[@verishabatool677]

Why we took 2L in the formula of surface tension

[@jhanolaer8286]

Why is the surface tension and spring force are the same unit?

[@dustbehindthehat2237]

I really love ur voice

[@hanaamin5671]

thanks a lot!

[@rutwiksadhale95]

If the cohesive force is higher then is it that there will be very less rise in capillary tube level?

[@amrshehata6012]

Thanks so much ❤️

[@yashodiptakore7599]

Why to take length of front and back of the rod ?

[@myeloon]

Because there are two surfaces to the fluid, front and back. Surface tension is present on both of them

[@rjk368]

@@myeloon Sorry if this is a dumb question, but what about the top and bottom edges?

[@myeloon]

@@rjk368 We just don't consider them in this case because there aren't any forces acting on them. We're assuming that the fluid would only change shape by expanding where we pull on the wire. The other sides would act exactly the same if we did the same to them. Hope I understood your question right

[@kannigakumar7602]

Water is present on front and back side of the rod

[@yanbingzhu4650]

@@myeloon Do you mean one layer of water has two sides, front side and back side? And both of them can produce surface tension?

[@mintesnotgezahegn5171]

Thanks a lot

[@muhammedlawal3726]

At 6:12 why did you multiply by 2 please

[@chibuzordesmond3937]

2L isn’t because you’re measuring front and back, it’s because you’re measuring the total length in contact which is 2dL + 2L = 2L

[@toxiclock1905]

Cud u elaborate

[@chibuzordesmond3937]

@@toxiclock1905 the material is assumed to have infinitesimal width, so the perimeter in contact would be the perimeter of the quadrilateral, 2L + 2dW
L is length
W is width, dW describes an infinitesimal width.
dW ≈ 0
2dW ≈ 0
Therefore, 2L + 2dW ≈ 2L, given the shape he describes in the video and the positions he says he's calculating for.

[@mattjaramillo712]

Soap(surfactant in this case) on water will cause a lot of surface tension enough to produce a bubble, foam, or enough structure to hold objects or items above the water because the soap will make a net to hold it

[@Callmeromain2016]

MISTAKE AT 6:46. Gamma is F/2L. So your answer for part b) is incorrect.

[@mamtaheda3246]

Yes because surface tension acts on two sides

[@Nightfall00-k4o]

Wow!
So much for detective conan profile pic eh?

[@tomatrix7525]

When calculating the work, he changed 2L to L and then said L(D) = Area but he is really saying L(2D) which is not Area, or would be Area(L)

[@ramazansafarov2331]

Yes I also noticed that and here should be W=2*y*L*dx

[@yanbingzhu4650]

Ｉagree.

[@synkernel730]

Think of it has: Area=LxW(which is same as 2L). Note that this formula (surface tension=F/2L) is for objects with two surfaces in contact with water surface while (surface tension=F/L) is for objects with one surface in contact with water surface. Why work=yA is because Lxd is same as LxL(metre2)

[@bendeguzbagosi2385]

@@synkernel730 Thank you so much

[@stefifortisea7370]

Thqnku

[@ahmedasmail9866]

Is this given area wire the area of ​​one face or is it the area of ​​both sides? Because if it is the area of ​​one face, we must multiply it by 2, but if this is the area of ​​both sides, then we put it as it is.

[@tershen9798]

Why did he multiply by 2v

[@azmaratesfay4012]

Where surface tension appears

[@sebastianlee2134]

is surface energy and surface tension similar?

[@seankaima8731]

❤

[@fortunekosisochukwu2074]

Normally, I'd easily understand your explanation but idk... there's just something you failed to make clear here. First of all, only explaining the theory aspect of this without the practical aspect makes it very hard to picture what's going.

[@fortunekosisochukwu2074]

Because earlier in the video, you said: y = F/L
Then you said: yA = W
Then later on, you said: y = W/∆A. I'm very confused 😕

[@iqrakhanamansari8670]

Is this 12th grade physics in USA?

[@patcornelius163]

If the net force on the water molecule at the surface of the water was downward the water molecule would accelerate downward. But they stay at the surface. The net force on the water molecule must be zero, give or take some jiggling about.

[@tomatrix7525]

He has so many ads

[@TheLakersfan24704]

YEAH YOU WAS WRONG ON 6:46 BUT YOU STILL GOT A CUTE VOICE THO ZADDY😉

[@Ashiq.Ibrahim]

wth

[@krisssssssu]

bruh-

[@tom_winguill]

σ

[@arnabzanbaishya7222]

it's not left, it's length

[@jollihotdog5196]

For people >= 140 IQ
Play it in a speed of 1.5

[@-.-Tobi._.]

Watched hole playlist in 2x speed :p

[@mahmoudyassine7952]

thanks a lot