Flow of fluids

The second hole allows air to fill the space emptied by the fluid. In B one hole is being used for both intake of air and out flow of the fluid.

Hasn't anybody here ever punched a hole in the bottom of a beer can before chugging it ?

think-

for barrel A-air will pass through the upper hole which will create an extra pressure to the water inside the barrel.if the air pressure is very high it will create a lot pressure on barrel A and the water flow through the lower hole will be faster.

example. $\text{when we open a bottle and drop the water it goes at normal speed.but when we pressurize the bottle from outside}$ $\text{the speed of the water flow increases.}$

for barrel B-as no external force is working water will come out at normal speed.

To explain this problem all you need to know is the fact that Barrel A has two holes on in the top and bottom Barrel B does not. Barrel A will empty faster because of the hole in the top allows airflow which would prevent air having to go in the bottom of barrel b to get oxygen to push more water out. Imagine if you were to take a glass bottle pour the water out it won't go but so fast because there is no airflow pushing the water out. But take that same bottle and drill a medium sized hole at the bottom that would let the airflow through the bottle letting it pour out faster.

Key solution is pressure. In A: atmospheric pressure+ pressure of air on top of liquid

Barrel A's hole at the top lets air in that would push the water down "barely" faster.

due to atmospheric pressure

Anytime when you try to empty a container with liquid in it, there needs to be some kind of matter to take place of the empty matter. In this case, the water will be able to freely flow out of the container with the air hole ventilation because as water is getting emptied, the matter exchange is constantly being filled with air. In the case of no hole or ventilation, there still need to be some sort of matter to replace the matter leaving, so air goes through the hole where the water is also getting emptied, and that's where you get that sound of gluging.

Since there is a hole on the top of barrel A, atmospheric pressure acts on the liquid which makes it flow out in greater pressure compared to barrel B in which there is no hole at the top thus less pressure is exerted on the liquid in barrel B which may even result in little or no liquid flow from it.

In barrel b both discharge of water and thereby intake of air is done by same hole thereby extending the length of time, assuming the volume of barrel and water is not negligible. :p

Becoz of atmospheric pressure in A... It gets empty first...

Pressure at the bottom of tank A is P=height of the liquidxdensity of the liquidxg + atmospheric pressure> pressure at the bottom of tank B only heightxdensityxg .Therefore discharge velocity of liquid at tank A is more than the tank at B(Bernouilli theorem; pressure converts to velocity )

Another way to think about this, volume "wants" to remain constant so the only way for this to happen is for the hole in bottom B to alternate between allowing air in/water out.. glug.. glug.. glug.. effectively cutting the fliw rate ~1/2.

Or if large enough to allow both to flow, reducing the effective area of the hole to allow some air in.

Hole in barrel A maintains atmospheric pressure on top of fluid surface in barrel A. Absence of hole and inturn absence of exposure to atmospheric pressure creates a vacuum inside barrel B when fluid flows out.

Air pressure will be added to the pressure off the liquid inside the barrel

It is due to the extra air pressure in A

air is the cause

The first barrel is using intake and outtake system that air flows through it therefore increases the speed of water dropping while the second barrel only has outtake so it is slower.