One straw drinking from many containers of liquid One of my friends brought up a photo:

Which sparked a debate about whether the containers closest to the end of the straw would empty first. I was just wondering if someone could explain if the closest two containers would be empty before the furthest.
 A: Assuming the straw(s) are full of liquid and you are sucking very slowly (so  we are just considering pressure, not fluid dynamics) the fluid levels in all the containers must be equal, otherwise the liquid would flow to equalise them.
A: The containers would empty at a different rate with a restrictive orifice separating the containers.  These straws may very well qualify. Without knowing the plastic viscosity and yield point of the fluid and an exact measurement of the ID, length and exact suction on the straw it can not be answered accurately.  BUT...Looking at the straws and knowing about how thick those things are and assuming an average sucker if you will I strongly suspect with this contraption the last containers would empty a bit more slowly. Also the side with the thicker fluid properties probably would be a bit slower than the thinner ones too.
A: Even with a Newtonian fluid like water and sucked very slow and constant the straw distances are not the same.  Thus the pressure drop at the lips would be different from each container making a very slight rate of suck difference. If not a constant rate suck it would attempt to level out on the flow back and probably would especially with a Newtonian fluid.  On the flow back cycle you still have the pressure drop difference but now the drop favors filling the closer containers more. With a Newtonian fluid you probably would hardly notice the difference.  There would be a difference.  A non Newtonian fluid like the ones in the drawing would exaggerate all of the above. The bottom line the suck is the last thing you do with no flow back and because of pressure drop there will be a difference.
