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adjurovich
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Let’s imagine a glass of water. Now, we press on the free surface of water with a spoon (just for example), will the pressure in the entire glass increase equally?
Thanks for help. I’ve been struggling to understand the term pressure because I would always think of directions… due to this definition: “it acts in all directions”. However, knowing that pressure is a scalar quantity, just like mass, I thought I should give it a different approach. Interestingly, when I did thermodynamics, the term pressure was perfectly intuitive to me (and still is when talking about gases), but with liquids it felt like a whole different story and I got lost. So I choose to apply thermodynamical approach to liquids too and that’s why I asked this question. I feel like I am slowly, but surely, connecting all information and knowledge I’ve gained so far about fluidsDale said:Yes. Is there some reason that isn’t clear to you?
If you person on the free surface with a spoon, the system will no longer be in equilibrium, and the spoon will begin descending into the fluid. The fluid at the surface of the spoon will be moving at the spoon velocity, while the fluid further away will be moving more slowly, and the fluid at the wall of the glass will not be moving. So the fluid will be deforming and, in terms of what Dale has pointed out, there will be viscous stresses developed within the deforming fluid, such that the state of stress is no longer isotropic.adjurovich said:Let’s imagine a glass of water. Now, we press on the free surface of water with a spoon (just for example), will the pressure in the entire glass increase equally?
The mental picture I have is of a spoon pressing down into the water without submerging. Like a tiny boat that is forced a bit into the water.Chestermiller said:If you [press] on the free surface with a spoon [...]