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Questions tagged [wetting]

21 questions
69
votes
2 answers

Why does wet hair keep its shape when it dries?

When I wash my hair and go to sleep, my hair is impossible to comb in the morning, stubbornly sticking to the shape it assumed during the night. The only way to get it right is to wet it again and comb it. What's the cause of this memory effect?
Petr
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55
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3 answers

How small does sand have to be to get wet?

I think of sand as a lot of very small rocks. Suppose I have a pile of rocks, each about 1cm in size, and the pile is a meter tall. If I pour a bucket of water on the rocks, most of the water will fall through the rocks and form a puddle on the…
Mark Eichenlaub
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9
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0 answers

When does water decrease or increase friction?

Water often acts as a lubricant e.g. a wet floor or road, but sometimes the reverse happens e.g. putting on wet clothes. I understand that surface tension is involved e.g. microscope slides sticking together, but are there other factors? What…
Gnubie
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8
votes
1 answer

Physics of dunking biscuits

Together with my 5 years old assistant, after endless observations breakfast after breakfast, we finally decided to be serious about it, and quantify a remarkable property of biscuits in milk. Surely, we are humbly trying to climb on the shoulders…
scrx2
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4
votes
1 answer

Height of a stable droplet on a perfectly wetting surface, shape of a water drop

I would like to clarify that this is not a homework question, but a problem that I chose to want to solve to satisfy my curiosity. I would like to understand whether the physical concepts I have applied and the physical situation I have modeled are…
M. A.
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2
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2 answers

Why do some objects tend to sink after some time in water even if they float at the start?

I have observed this phenomenon in swimming pools: I have seen many dead insects floating on the surface, but after some time some they tend to sink down without any external influence. Why does this exactly happen? It even happens with paper: When…
Naveen V
  • 668
2
votes
0 answers

How to make straight wetting angle between water and glass

Looking for any liquid (preferably non hazard and transparent) which is immiscible with water in order to make a 90 degrees wetting angle with glass. Water+liquid should from a 90 degrees wetting angle on a glass surface. Colour doesn’t matter since…
2Napasa
  • 161
2
votes
1 answer

Reason for motion of a fluid

I was making coffee for myself, when I observed that when I poured coffee from the frying pan (having curved edges), the fluid went directly into the cup without falling; but when I transferred coffee from one cup to another at a particular…
imposter
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2
votes
1 answer

What determines the size of a straw/pipe to stop a liquid running out of it when closing one end of it?

When I put a finger on a straw with water in it, it wouldn't fall out of this straw. But is there maximum size (length and diameter) of this straw/pipe to get this effect and what causes this limit?
Marijn
  • 3,408
2
votes
1 answer

Why is the liquid surface concave when it wets a container?

As you can see in this diagram the surface of the liquid is concave, why is the part of the liquid surface adjacent to the container has higher height than the rest of the surface, is it because it's not surrounded from all directions by molecules…
user2390934
  • 43
1
vote
1 answer

Derivative of volume with respect to surface area in Young-Laplace $\frac{\partial V}{\partial A}=(1/R_1+1/R_2)^{−1}$

While studying Physical chemistry of interfaces, from: Page 42 (chapter 3 , section on "equilibrium conditions") in Butt, H. J., Graf, K., & Kappl, M. (2013). Physics and chemistry of interfaces. John Wiley & Sons. I encountered the following…
Dr. John
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1
vote
1 answer

Which kind of paper has highest absorption speed?

I am experimenting to analyse the liquid wicking(radial) behaviour of various liquids. I have performed initial studies and experiments on household paper towels but they tend to deform and stick to the surface they are lying on, when wet, as shown…
ashish.g
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1
vote
1 answer

Stainless Steel in Kitchen Dishwasher Doesn't Dry

I find that stainless steel tools, especially the shiny ones, stay wet after the (no heat) dry cycle while ceramic plates are dry. The water beads on the shiny surfaces but perhaps less on rougher and thicker tools. I don't use a rinse aid. What…
Incredible II
  • 435
1
vote
3 answers

How does surface tension prevent a pin from sinking?

Please explain simply how surface tension in water which as far as I understand is a force pulling the water molecules at the surface towards each other horizontally so how does that prevent a vertical gravitational force downwards , also the water…
Potato
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Drop of water in zero gravity

Suppose there is a drop of water in gravity-free space. A man slowly touches the drop and keeps his fingers touched. What happens? Does the drop change its shape? Or wet his fingers? Or there is no change? What if I take mercury? Note: Consider no…
user114592
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