Douglas Summers
Member
Good teaching post. HOH chemistry was my profession (retired. now after approx. 40 years)Oh, I see, you are talking about them seeking their own level as height differences due to pressure, not a level flat surface as I assumed.
Seeking their own level, to me, means that every given point on the surface of a liquid will be exactly the same height.
What you are talking about in the "U" shaped tube, is pressure equilibrium's. The example you quoted works that way due to the mercury putting more pressure on the liquid in the very bottom of the tube. The weight of the liquid on each side of the very middle of the tube, at the bottom, must be the same.
The surface of a lake, however, will always reach a perfect level unless acted upon by a force, like wind.
Also, right at the side of a container, liquids will form a meniscus. A concave meniscus is where the liquid curves up at the edges of the container. This is because the molecules of the liquid are more strongly attached to the container material than themselves.
If the meniscus curves down and forms a convex meniscus, it means that the liquid is more strongly attracted to itself than the material that the container is made from.
Mercury will form a convex meniscus in glass while water will form a convex meniscus.
If the container is large enough in diameter, both liquids will be perfectly level in between their menisci while being at different levels in the tube from side to side.
As for ocean sea levels... I saw these explanations....
The Pacific is less salty and so less dense and so higher and various local current issues make it locally a few centimeters higher than the Atlantic right there. Sea level is not the same around the world.
Talking about the Panama Canal....
It's not really - the difference is only a matter of centimeters and basically it's due to currents and weather conditions. There is no significant difference in sea level on each end.
Or just outright denial...
There is no difference in sea level in the Pacific or the Atlantic Oceans