How does a straw work?
Hi. I know its because of pressure but can you please explain it without using the term: "pressure." Another question: Is pressure the same as the weight of air? Does it mean there is less air in one place and more in another? Please give a kid-friendly definition of pressure
Update:Is light air less dense
Comments
Pressure from your mouth and the air pressure causes pressure to pressurize the pressure into your pressure hole.
Grintable has it. But I'll try a slightly different approach.
"Atmospheric pressure" the force that air exerts, is 14.7 pounds per square inch. The simple explanation would be that that is because there are 14.7 pounds of air above that square inch. But it is not quite that simple. In fact fluid dynamics seem a bit strange sometimes.
In, I think, the 1600s - but it may have been earlier - there was a sort of trick that people would perform in London. They would take a long thin copper tube and connect it, without any leaks, to the top of a sealed wooden barrel full of water, so that the tube stuck up into the air for 20 feet or so. And they would take a pint of water and pour it into a funnel at the top of the long thin tube. The tube would fill, and from adding just one pint of water, the barrel would burst.
Because the pressure in fluids is only dependent on the height of the fluid, not the actual amount of water or air that is above it. So the pressure you get from air is in all directions and does not depend on the shape of the, let us say, opening, to the air above. That is why the pressure is the same in a dark cellar as out in the middle of a huge plain.
By expanding your lungs, you area able to lower the air pressure in your lungs, and then you lower it in the straw. The force on the water in the glass is unchanged, and so it is a little like a see-saw, with the 'outside air' staying the same, and the 'inside air' getting lighter, so the lighter end of the seesaw moves up.
Pressure is force on a given area. A straw works when the drinker creates an area of low pressure inside the tube. Because of the tendency for an area of higher pressure to flow to an area of lower pressure, the water comes up the straw and into your mouth. Pressure is indeed based on the weight of air, increases or decreases in heat/humidity will increase or decrease the air pressure, because of this, there are different levels of air pressure in relatively close regions.
Ok...without using the word pressure.
The deal is, the entire atmosphere pushes on all surfaces in all directions.
So, at the top of your glass, the atmosphere pushes down on the water.
If you do not do anything with your mouth, you have an ordinary parcel of air in it, which also pushes down on the water in the straw.
When you expand your cheeks and expand the air, there is less pushing of the air on the water in the straw, and it isn't anymore preventing water from flowing upward, but rather just lets water flow as it would.
Suction doesn't really exist. It is just a lack of push from a less full container than the initially pre-filled container of air.
Suction is really just the background air pushing objects in to the more evacuated regions.
------------------
Definition of pressure.
Our background pressure is DUE TO the weight of all the air above it, as it is supporting the upper atmosphere....but no it isn't the same thing as weight.
Pressure is force per unit area. Fluids locally push uniformly outward in all directions, no matter what their loading situation. That "push" per unit localized area of a "target solid" or even target fluid, is what we call pressure.
Pressure? Kid you dont know a thing about pressure..
And effin straws, they just work.. Tell your damn teacher that they do their damn job bc they damn do, and they do a damn fine job at that.. unless you get one of those stupid bendy straws.. I mean wth are those about.. I cant move my head another inch so heres a bendy part for ye. silly straws tho.. fantastic.
ALSO.. I think its suction.. ask your teacher.. they will know all about sucking.
but heres this..
replace the word 'pressure' with "elfin magic"
This is all thanks to Air "elfin magic"and liquid "elfin magic". Lets say that you are drinking nesquik from a glass with the help of a straw. When you suck at the straw, you are essentially drawing air out of the straw. This decreases air "elfin magic"which was in the straw right above the level of the liquid. In the mean time the air "elfin magic"around your glass of liquid is constantly pushing the drink level to go down. And the water "elfin magic"of your drink is pushing the liquid level to go up. Since you just helped decrease the air "elfin magic"in the straw, the liquid finds an outlet and thus goes up the straw till it reaches your mouth with all the delicious nesquik.
wikianswers ftw.. srsly..
a straw works because when you suck in you remove the air from the straw making the liquid replace the air moving it up the straw.
pressure is not the same as the weight of air it is the density of air the higher the density the more air there is in that spot the lower the density the less air is in the spot