0
$\begingroup$

If I have two 20ml test tubes connected at the base via a thinner flexible U-shape tube and I pour a set amount of water (40ml) into one test tube whilst both are at level height, the water equilibrates so that it is at the same level in each tube. If I then introduce a stopper to meet the surface of the water in one tube and raise the other open tube to a higher level of lets say 2cm, how can I determine the pressure exerted onto the stopper by the water as the system once again tries to reach equilibrium? I'm not sure what equations I need in order to work out everything that is going on in the system. I'm trying to mimic a certain pressure against the stopper but first need to understand what the current pressure is and what factors I am working with in order to change the height of the other tube to gain the pressure I am after. Below is a simple schematic of what I mean, any help to get me started would be great - thank you!

enter image description here

$\endgroup$
2
  • $\begingroup$ Are you familiar with the equation $\Delta p=\rho g h$ $\endgroup$ Commented Jan 6, 2021 at 12:36
  • $\begingroup$ Thank you - this makes sense, I thought it would be more complicated. $\endgroup$ Commented Jan 6, 2021 at 13:30

1 Answer 1

0
$\begingroup$

Pressure tubes

The pressure at the top of the left hand tube is simply given by Pascal:

$$P=P_0+\rho g h$$

where $P_0$ is the atmospheric pressure.

$\endgroup$
1
  • $\begingroup$ That's great, thank you so much for the schematic. I see now that it is a simpler situation than I thought. $\endgroup$ Commented Jan 6, 2021 at 13:31

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.