Inverted Bottle, Air Pressure, Hole Size ```Name: Jent Status: Student Grade: 6-8 Location: Outside U.S. Country: Sweden Date: Winter 2009-2010 ``` Question: If you have a container with a hole (a relatively small one) in the top and you fill it with water and then put it upside down, the water will not flow out! why? What happens with the water when I make the hole twice as big? Will the height of the water be half of what it was the first time? And what is the relationship between those two things, size of the grid hole and height of the water in the container? Replies: Jens Q1: If you have a container with a hole (a relatively small one) in the top and you fill it with water and then put it upside down, the water will not flow out! why? A1: The water will not flow out because the hole is not big enough. Q2: What happens with the water when I make the hole twice as big? A2: Try it and find out. I cannot tell you because I do not know if the bottle is glass or plastic or how big "twice as big is." Try slipping a thin piece of straw from a broom or something into the hole and when water starts dripping down the straw, air might be able to start slipping in. Once that happens, once the vacuum (reduced pressure) at the top of the bottle that is holding in the water, all of the water will drain out of the bottle. Q3: Will the height of the water be half of what it was the first time? A3: No, once the water starts flowing through the larger hole all of the water will drain out. Q4: And what is the relationship between those two things, size of the grid hole and height of the water in the container? A4: The relationship is that once the hole is big enough to let water pass out and air pass in, all of the water will flow out of the container. Once the hole is big enough to allow water to flow out and air to flow in, the vacuum (lower pressure) at the top of the bottle which holds the water in will fill with air and there is nothing left to hold the water in the bottle. Sincere regards, Mike Stewart Click here to return to the Engineering Archives

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