Recent content by tjm2444

But aren't you saying here that the pressure in the pipe is simply the hydrostatic pressure? Is the water moving at point 2? If so, then the pressure at 2 is lower than the hydrostatic pressure.

First, thank you for understanding my question, bone3ead! Most texts say that Bernoulli's Equation applies to any two points along a streamline. Is there no streamline that can be traced from the free surface on one side to that on the other? And if there is (which I believe is the case)...

Your notes suggest that you think that a free surface that has descended a height h is moving at a speed √2gh.

I don't need to ask because I understand how you arrive at each of your equations. The v = sqrt (2gh) result is standard, and I've derived it many times on my own. Yes, and now you're applying Bernoulli's equation to the same free surface at two different times, with the result that the...

One last time, yes it does. See image.

When you apply Bernoulli's Equation to two points -- the free surface on each side -- it yields h = 0. Clearly this is a misapplication of Bernoulli's Equation, but why? What is wrong with using those two points? Thanks for trying to help.

Points 1 and 2 are at the surface in each container. If the containers have the same diameter, then v1 = v2.

It doesn't matter how the cylinders are connected or whether or not there are valves. We can start with one empty and one full, and then apply Bernoulli's equation at the time the situation is as depicted in my diagram.

Sure. The initial state is as shown, and the process starts by opening a tap.

OK, let's work through this: v1 = v2 because the cylinders are identical. P1 = P2 because both points are at the atmosphere. So we get h = 0. What did I do wrong?

OK. Why can't we start the process with initial conditions as they are in my diagram, and why does the application of Bernoulli's Equation to points 1 and 2 yield the non-sensical result that h = 0 in that case? I'm not accusing Bernoulli's Equation of being wrong, I'm simply trying to...

Because the cylinder's have the same cross sectional area, as I said in the original post.

I'm familiar with your analysis. My question is why does applying Bernoulli's Equation at points 1 and 2 in my diagram give h = 0. Applying Bernoulli's Equation in this way yields the same result whether it's a siphon, or if the vessels are connected by a pipe at the bottom.

In the diagram attached, Bernoulli's Equation applied to points 1 and 2 gives h = 0, which makes no sense.

I understand that, but my question is why Bernoulli's Equation give nonsensical results when applied to the liquid surface on each side.