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Name: Vladimir L.
Status: Student
Age: 12
Location: N/A
Country: N/A
Date: N/A

I am doing an experiment on hydraulics. The question I am trying to answer is: What is the relationship between pressure and tube diameter for a flow of liquid? I wanted to see if there is more water pressure in a tube with a large diameter or a tube with a small diameter. The large diameter tube had more pressure, Why?

What you are looking into is know as Pascal's Principle of Fluids. Understand that a fluid is generally defined as a gas or liquid that is contained. So, a fluid can be air, water, oil, etc. So if we have a fluid in a contained space and pressure is applied to the fluid, Pascal's Principle states that this pressure is transmitted through the fluid undiminished with equal force on equal areas. The key words are equal force on equal areas. If the areas are different, the forces will be different and thus the pressures different. Pressure is defined as force per unit area, and area is related to the diameter of the tube. So, I recommend that you go to your local library and look for a book on hydraulics to get an idea what Pascal's Principle (or some books may call it Pascal's Law) is. Ask your librarian to help you find a book that is less mathematical and more technical so you can get a better idea on how things work without all of the theory. Please feel free to write back if you have more questions. It sounds like a really good experiment.

Thanks for using Newton.
Chris Murphy

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