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kishtik
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I'm walking on a beach, it's sunny and hot. When I step on the wet sand it becomes dry! Why?
Where did this happen? I've never made wet sand dry by walking on it.Originally posted by kishtik
I'm walking on a beach, it's sunny and hot. When I step on the wet sand it becomes dry!
No, I didn't mean that. The sand under my foot was drier.Originally posted by UltraPi1
I think I get what kishtik is talking about.
My reply would be that the sand around your foot is raised higher than what it was before you stepped on it, and when this happens the water drains out. Essentially you raised the sand above the water table.
Well then it would be a little of both explanations. The sand under your foot while it's still in the sand would still be wet, although less water per volume. Lifting the foot would release the pressure thereby allowing the sand to raise slightly in which the water would flow out before it flowed back in.No, I didn't mean that. The sand under my foot was drier.
Originally posted by Chi Meson
If you lay a piece of Scotch tape on a flat surface (like glass), so that it is NOT stuck; then you use a fingernail to swipe across the tape, making a thin line that IS stuck to the surface; then you pull the end of the tape straight up. YOu will see that the line of adhesion propagates along the tape-surface. IT's quite nifty.
Please explain wider. Does the sand behave like a spring?Originally posted by UltraPi1
Well then it would be a little of both explanations. The sand under your foot while it's still in the sand would still be wet, although less water per volume. Lifting the foot would release the pressure thereby allowing the sand to raise slightly in which the water would flow out before it flowed back in.
Originally posted by phatmonky
Expand on this please... A quick test, and I don't follow what is so amazing about what I just did
Lever action? When you pull up on one end, the pivot point is the line that is stuck, so the other end goes down. But, by going down, it will come into contact with the table.Originally posted by Chi Meson
It's not earth-shattering, nor is it "unexplainable," but why does the tape not simply come unstuck and lift straight up?
I wonder whether this 'drying' effect would work if the sand grains were all sperical and of equal size. I suspect not - or at least a lot less. For water to be squeezed out of the sand, the space between the grains must decrease due to the foot pressure. The arrangement without your foot must be a minimum energy configuration and this would involve energy due to adhesion and cohesion of the water ('capilliary' effects)- altering the spacing / rotation of the sand particles.
Adding some local pressure could be expected to change the situation and the resulting arrangement could well involved reduced volume between the particles by making them rotate and forcing them closer together.
I don't think this, short term, effect is associated with hydrostatic pressure, which will take longer to affect things; eventually the water would soak back in and the sand settle down into a new equilibrium arrangement.
The sun's heat causes the water molecules in the wet sand to evaporate, leaving the sand dry.
The sun's heat is more intense than the ambient temperature in the shade, causing the water to evaporate at a faster rate.
It is generally safe to walk on wet sand in the sun, but it is important to be cautious as the sand can become very hot and potentially burn your feet.
The drying time of wet sand in the sun can vary depending on factors such as temperature, humidity, and the amount of water present. Generally, it can take anywhere from a few hours to a full day.
Yes, darker colored sand will absorb more heat from the sun and therefore dry faster than lighter colored sand.