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Where does ocean pressure come from?

  1. Nov 18, 2013 #1
    I did my research and the answer I got is deeper I go the more weight from the water above me that I have to handle just like lifting weight. Like in the picture below


    It is reasonable that I will feel the pressure on the top of my head and on the upward side on my arms ( like in the picture) due to the effect of the gravity pulling the water down. But how can I still the pressure everywhere else like on the bottom on my legs, my left side body, every single point on my body. Gravity can't pull the weight upward right?
    my little theory is the water molecules have something to do with this. Since they moving around rapildly. they will crash into our skin molecule (our body molecule) and create pressure. I hope you guys can explain this to me. Thank you.
  2. jcsd
  3. Nov 18, 2013 #2


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    Well, consider a small element of water in a still water tank. This element has pressure forces acting on all sides of it and is not moving since the water is still. If the pressure was only acting on the top, then the element of water would be constantly accelerating downward, just like if the pressure on the top and bottom or either side was different, but we already know that the element is stationary. What this means is that at a given point in the water, the pressure is acting equally in all directions. This means that if you are floating under the water, the upper, lower, and side surfaces of your body are all feeling pressure based on their depth in the water.

    This phenomenon is called Pascal's law.
  4. Nov 19, 2013 #3
    I got it but "This element has pressure forces acting on all sides of it and is not moving since the water is still". I know that element for example a teddy bear maybe will be affect from any direction on Every single point on it body by the pressure.I know it's there but where does it come from. what cause it?
  5. Nov 19, 2013 #4
    When the water molecules get squeezed together by the overburden weight, they push sideways and upward also.
  6. Nov 19, 2013 #5
    If you squeeze a balloon between your fists, it doesn't just press against against the your fists. It squeezes out the sides and will even try to go around your fists if its big enough. It will deform and bulge out everywhere it can to get out of the way of your fists. Same goes for the water.
  7. Nov 19, 2013 #6
    Here is what I got:


    when being affected by the the forces come from the weight of the water molecules above them (1 and 2)
    1 is the force from gravity pulling the molecules down
    2 is created just like the floor when you push a balloon toward the floor. Then the floor will send back the same amount of force ( Newton). Same thing in this case I believe.

    When 2 molecules are being forced , they will bounce out in random directions (like 3 -> 6)
    then they will crash into the object A . That's how pressure is created.
    In deeper level, there will be more pressure due to the increasing of forces number 1 & 2 ( more water molecules are above them equal more weight they have to handle). So those 2 molecules to receive more energy. They will travel even faster and crash harder into the object A create stronger pressure

    In conclusion, sea pressure is created due to the water molecules' rapid movement and their impact with the object A.

    That's what I got. please feel free to correct me and explain further if I'm wrong. Thank you guys for bearing with me . Thank you again in advance.
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