Answer by arivero for Mechanics around a rail tank wagon
Adding another answer here mainly to document the known sources of this problem. Further references can be checked in https://arxiv.org/abs/2001.09807, The physical leaky tank car problem, by S....
View ArticleAnswer by Gerard De Santis for Mechanics around a rail tank wagon
As the problem is initially described, the nozzle is located on the left bottom side of the tank with the nozzle exit facing downward. if this is the case, there will be no horizontal force to act as a...
View ArticleAnswer by arivero for Mechanics around a rail tank wagon
Some years later... I am reviewing this problem mostly for my own benefit, But it could be useful if somebody is still wanting to discuss the answers, particularly without any braking system.let me...
View ArticleAnswer by arivero for Mechanics around a rail tank wagon
With a vertical jet, Torricelli's law still holds because the displacement of the wagon is orthogonal to the acting forces, gravity plus (arguably, but orthogonal in any case) reaction force, so no...
View ArticleAnswer by Mark Eichenlaub for Mechanics around a rail tank wagon
This answer presents an analogy that I hope will clarify how it is possible that 1) the wagon moves 2) the wagon winds up with a net velocity at the end of the problem. This isn't a direct answer -...
View ArticleAnswer by Lukas for Mechanics around a rail tank wagon
Short version: movement inside the closed system cannot accelerate it. Zero horizontal speed at exit means zero speed at t->infinity. More detailed version:Let me transfer the problem to a simpler...
View ArticleAnswer by David for Mechanics around a rail tank wagon
Interesting problem. I think my approach and answer is very close to other posted solutions. I also added a possible scenario. The basic summary is it is the change in the average momentum of the water...
View ArticleAnswer by Sklivvz for Mechanics around a rail tank wagon
A quantitative answerThe three main conservation laws of fluid mechanics areConservation of massConservation of momentumConservation of energyReferenceBetween the time $t$ and $t+\mathrm{d}t$ a mass of...
View ArticleAnswer by Frédéric Grosshans for Mechanics around a rail tank wagon
OK, that is my second tentative to solve this problem. I think I have a solution this time, thank to the discussion of others in that thread. The solution is...
View ArticleAnswer by Martin Gales for Mechanics around a rail tank wagon
Here is my attempt. I went to a somewhat different path than kalle43 and this is a little easier i think.Let $x(t)$ be the coordinate of the nozzle at time $t$. Consider an infinitesimal mass of water...
View ArticleAnswer by Mark Eichenlaub for Mechanics around a rail tank wagon
Qualitative AnswerI think the cart exhibits an extremely surprising behavior. The cart begins by sitting still on the track. The hole is to the left of the center. When the nozzle is opened, water in...
View ArticleAnswer by Frédéric Grosshans for Mechanics around a rail tank wagon
My answer below is wrong: it doesn't take into account the momentum of water leaving the cart once it has started moving.Basically, by conservation of the horizontal momentum in the absence of any...
View ArticleClik here to view.
Answer by Sklivvz for Mechanics around a rail tank wagon
Clearly the water going out of the nozzle does not contribute any horizontal momentum change. Initially the wagon is still and the water flows downward.The only reason why the wagon could move is that...
View ArticleClik here to view.
Mechanics around a rail tank wagon
Some time ago I came across a problem which might be of interest to the physics.se, I think. The problem sounds like a homework problem, but I think it is not trivial (i am still thinking about...
View Article
