Can anyone help me out with fluid mechanics

In summary, the problem involves an open-ended can filled with air at atmospheric pressure and at a temperature of 70 F. The can is then immersed in water and the question is to find the height of the water inside the can. The can is immersed at a depth of 10 feet into a water tank open to the atmosphere. One approach to solving this problem is to consider the can and the water inside it as a system and use the relationship between the pressure of the compressed air and the pressure of the water to find the height of the water. Another approach is to use Boyle's law to determine the amount of compression that can be achieved by the air column in the can. Without further data, the problem cannot be solved.
  • #1
rogga
1
0
hello,
i am having some troubles with this problem. please take a look and help me if you can.

an open-ended can 1ft long is originally full of air @ 70 F. the can is now immersed in water. assuming that the air stays at 70 F and behaves like an ideal gas,how high will the water rise in the can? the is immersed at 10 ft deep into water tank open to the atmosphere.
thanks in advance. please show the work

i tried to find the pressure of the water at the bottom of the tank. then i assume x to be the height of the water in the can with the air on top of it. considering the can as the system now, there is a relation between the compressed air in the can and the water inside the can. the pressure at the bottom of the can which is also equal the pressure at the bottom of the tank, will be the sum of that of the air plus dgX of the water (density* gravity* X) with X being the height iam looking for. i have this one realtionship and i can't think of another one to get the height X out of it... can anyone help?
 
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  • #2
Welcome to PF!

Hello rogga! Welcome to PF! :smile:
rogga said:
an open-ended can 1ft long is originally full of air @ 70 F. the can is now immersed in water. assuming that the air stays at 70 F and behaves like an ideal gas,how high will the water rise in the can? the is immersed at 10 ft deep into water tank open to the atmosphere.

i tried to find the pressure of the water at the bottom of the tank. then i assume x to be the height of the water in the can with the air on top of it. considering the can as the system now, there is a relation between the compressed air in the can and the water inside the can. the pressure at the bottom of the can which is also equal the pressure at the bottom of the tank, will be the sum of that of the air plus dgX of the water (density* gravity* X) with X being the height iam looking for. i have this one realtionship and i can't think of another one to get the height X out of it... can anyone help?

Well, that looks ok … I don't understand why it doesn't work. :confused:

Show us the equations you got. :smile:
 
  • #3
rogga said:
hello,
i am having some troubles with this problem. please take a look and help me if you can.

an open-ended can 1ft long is originally full of air @ 70 F. the can is now immersed in water. assuming that the air stays at 70 F and behaves like an ideal gas,how high will the water rise in the can? the is immersed at 10 ft deep into water tank open to the atmosphere.
thanks in advance. please show the work

i tried to find the pressure of the water at the bottom of the tank. then i assume x to be the height of the water in the can with the air on top of it. considering the can as the system now, there is a relation between the compressed air in the can and the water inside the can. the pressure at the bottom of the can which is also equal the pressure at the bottom of the tank, will be the sum of that of the air plus dgX of the water (density* gravity* X) with X being the height iam looking for. i have this one realtionship and i can't think of another one to get the height X out of it... can anyone help?

Hi there,

I don't know what equations you are actually using but as far as I see the air inside the can is at atmospheric pressure. At the bottom of the tank, the pressure on the air column is equal to water pressure at that depth. Now the air experiences a pressure of (water pressure - atmospheric pressure). That's what compresses it. Now the problem is reduced to finding out how much compression can be achieved by this net pressure. You have a 1 foot column of air in the can. Now when the air is compressed the pressure inside the column increases at the cost of volume. Boyle's law tells us that. And the air continues being compressed till the air pressure in the can equals the water pressure. Now the water pressure is no longer that pressure of water which it was at 10 feet depth because remember, the water has risen. I hope I have given you a lead because without further data I cannot solve this problem...
 

1. What is fluid mechanics?

Fluid mechanics is the branch of science that deals with the behavior of fluids, which can be both liquids and gases, and their interactions with solids and other fluids.

2. Why is fluid mechanics important?

Fluid mechanics is important because it helps us understand and predict the behavior of fluids in various situations, such as in engineering designs, weather patterns, and biological systems. This knowledge is crucial for the development and advancement of many industries and technologies.

3. How can fluid mechanics be applied in real life?

Fluid mechanics has many practical applications, such as in designing airplanes and cars, predicting weather patterns, designing water and sewage systems, and understanding blood flow in the human body. It is also used in fields like oceanography, meteorology, and chemical engineering.

4. What are some basic principles of fluid mechanics?

Some basic principles of fluid mechanics include the conservation of mass, conservation of momentum, and conservation of energy. These principles help us understand how fluids behave and how they can be controlled or manipulated.

5. How can I improve my understanding of fluid mechanics?

To improve your understanding of fluid mechanics, you can study textbooks and attend lectures or online courses. It is also helpful to practice solving problems and conducting experiments to apply the principles you have learned. Collaborating with other scientists and discussing concepts with them can also enhance your understanding of fluid mechanics.

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