# Help with at home experiment for physics degree: how to suck water up a tube

I'm doing an at home experiment for my physics degree due to covid restrictions, and I need to suck water up a vertical tube. I would really appreciate any equipment recommendations or other advice you could give me, as I'm not very practical and I'm not sure how to put everything together to achieve what I want.

Let me describe the problem in detail. The bigger picture is that I want to put a vertical tube in a tank, draw water up the tube, then release the water so that it drops back down the tube and oscillates up and down within the tube. What I need to figure out is a cheap and simple way to draw the fluid up the tube initially.

The tube must be rigid, straight, and transparent. The tube will be about 1m in length, and I would like to be able to draw the fluid nearly to the top but not all the way to the top where it'd overflow. I must be able to draw the fluid slowly enough that I could precisely set the height anywhere in the tube. The tube diameter is not yet decided, but I would be happy to use standard sized pipes and fittings, ideally a tube between 0.5-2cm in diameter would be good (but I'm flexible on this).

I was thinking that I'd need to put a valve on the top of the tube, use a suction pump to draw water up the tube, then seal the valve, and when I'm ready to drop the fluid, quickly open the valve again. It would be a bonus (really not necessary if it's not very easy to incorporate) if I could get an accurate pressure measurement of the air inside the tube before I drop the fluid. Also, once I open the valve I don't want it to restrict air flow too much as this would stop the fluid falling freely. I want the pressure in the tube to near instantly reach atmospheric pressure after opening the valve.

I'd like to achieve all this for under £50 (ideally quite a bit less than that). I'm in the UK, so please could you recommend parts that I'd easily be able to obtain here.

(I suppose one alternative method is that I could pump water into the bottom of the tube, seal a valve at the top of the tube, then remove the pump apparatus from the bottom of the tube before opening the valve again.

I am aware I could also lower the tube into the tank, seal it, then lift it up, but this isn't viable for me as I won't have a deep enough tank to be able to get the water far enough up the tube.)

• What is the tube inside diameter and length? Commented Jan 23, 2021 at 23:29