tanks

Classical Mechanics Level 1

In the diagram, which tank will become full first?

Details and Assumptions:

Water flows out of the faucet so slowly that the flow never exceeds the carrying capacity of the pipes.
All tanks are open at the top. All pipes have equal diameters.
The centers of the tops (and bottoms) of the tanks all lie in the same plane. So, tanks that are higher in the diagram are actually higher.

2 3 4 5

3 solutions

Avik Das
Oct 15, 2017

It is very clear that the height of the pipe 3 is lowest.
So from the principle of occuring same height of water, the pipe 3 will be full at first.

It's a bad drawing, it appears to mix 2D and 3D.Making the answer ambiguous.

Richard Ingels - 3 years, 7 months ago

I thought 2 and 3 were up in the air, and that 4 and 5 were on the ground. Apparently, all but 1 are sitting on the same plane, which isn't clear from the drawing. If 4 and 5 were the only tanks on the ground, they would be the lowest, and gravity would fill them first, and since 4 is shorter than 5, 4 would fill, and start overflowing before 5 ever got filled, I think.

Cedric Revefrand - 3 years, 7 months ago

Actually, even if that were true, 3 would fill first because it still has a lower top than them, which matters.

Ayush Kumar - 3 years, 7 months ago

This is not necessarily true because, as seen in tank 1, it fills a little but then never gets higher than a certain point.

Ayush Kumar - 3 years, 7 months ago

Wrong its the tank with the lowest brim (or lowest height) that will overflow first.

Brian M - 3 years, 7 months ago

i.e tank 3

Brian M - 3 years, 7 months ago

This is interesting. Why is it the case that water always stays at the same height?

Agnishom Chattopadhyay - 3 years, 7 months ago

It looks to me that pipe TWO is the lowest. VERY POOR DRAWING!Ever heard of angular perspective? CLEARLY pipe TWO is the lowest. UNFAIR QUESTION!

Lawrence Rowswell - 3 years, 7 months ago

You are correct... bad question... if assume the containers are all sitting on level ground, 2 is clearly the shortest.

Robert Sproull - 3 years, 7 months ago

the solution is wrong drawing a line somewhere does not make the solution right tank 2 has the smallest height so it will fill and overflow before the others That is simple hydraulics

bill boyd - 3 years, 7 months ago

Why would the tank with the smallest height fill first? Tank 3 opens lower than tank 2, so how can tank 2 fill up before tank 3 fills up?

Pranshu Gaba - 3 years, 7 months ago

Simple its height (brim) is lower, so tank 3 will overflow while the others are still filling

Brian M - 3 years, 7 months ago

i didn't understand nothing about this

Erick Garcia - 3 years, 7 months ago

Presume you mean tank with the lowest brim (top)

Brian M - 3 years, 7 months ago

Im having difficulty with what type of concept the problem is attempting to apply. Can any one help? Im trying to structure my thoughts in a simple and concise system in order to better understand the answer, so if possible please make a list of concepts applied.

Luis Ramirez - 3 years, 7 months ago

Ayush Kumar
Oct 11, 2017

The water will flow to the lowest point initially (ignoring the level to get to the pipes because the tank isn't full even then). After the water reaches the pipe from 3 to 5, tanks 3, 4, and 5 will even out and start to have the same water level. $\boxed{3}$ has the lowest top among these so the water will reach there first. It will be followed by 2, 4, 5, and last would be 1.

I disagree with the last sentence of your answer. Given the two assumptions listed in the problem, tank 3 would overflow, and none of the other tanks would ever fill. 1 would fill to the level of the bottom of the pipe leaving it, the rest would fill to the height of the top of 3.

Stephen Colodner - 3 years, 7 months ago

I am assuming that the tanks had a top, stopping them from overflowing.

Ayush Kumar - 3 years, 7 months ago

Height of tank 2 seems to be the lowest

RAHUL KUMAR - 3 years, 7 months ago

Don't copy another without knowing the actual reason

avik das - 3 years, 7 months ago

What do you mean i was the first person to post a solution on this problem. I posted it before it was a prolem of the week as well.

Ayush Kumar - 3 years, 7 months ago

Your solution was of 2 lines. And after I wrote my solution, your solution becomes larger.

avik das - 3 years, 7 months ago

Tim Gallacher
Oct 17, 2017

Tanks 3, 4, and 5 all communicate via multiple equalizing lines. Since all are open to atmosphere, and liquids seek their own level, the lowest tank will fill and overflow first, leaving all other tanks partially empty.

Had you made it clear that all tanks were in the same vertical plane I would have answered differently. The drawing appeared to be in perspective to me.

Ian Stain - 3 years, 7 months ago

After the lowest tank fills up, will any other tank fill up at all?

Agnishom Chattopadhyay - 3 years, 7 months ago

No as tank 3 will overflow.

Ian Stain - 3 years, 7 months ago

Luis Ramirez - 3 years, 7 months ago

tanks

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