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[sharon567]

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Hi there,

i was wondering if someone could help me with this problem i have to create an algebraic expression for the following manometer. I have to present a formula that can be used to determine the specific gravity of the unknown fluid in terms of various column heights please see attached diagram.

Any help would be greatly appreciated.

[Art Montemayor]

Sharon:

More than 50% of any student's problem is in the fact that he/she cannot communicate efficiently or accurately. For example, what is the mysterious "unknown fluid"? Is it found in the shaded portion of the manometer by any chance? If so, why don't you make it easier for those persons that you are asking for help by pointing this out? Don't you think that you could possibly be helping your own self obtain help if you made it easier and clearer for your readers to fully understand and comprehend what your problem is, how much of your own problem you have tried to solve (and how), and what part is the part that you don't understand?

The best help you can obtain is probably in your own Static Fluid Mechanics text book (where this problem probably originated). Tell us the whole story: are you presently taking a course where you were assigned this problem? are you having problems understanding your professor or instructor? are you having problems understanding your text book? What text book are you studying? Have you studied other text books? Have you studied other sources in the Internet?

All these points mentioned above would be of help in helping you out. In the meantime, let me alert you to the fact that these Forums are not a free source for doing your own homework assignments. We will help you. We won't do your work for you. Send us the information to help you out.

[sharon567]

 homework_202_20_chaper_203_.pdf   751.65KB   64 downloads

Sharon:

More than 50% of any student's problem is in the fact that he/she cannot communicate efficiently or accurately. For example, what is the mysterious "unknown fluid"? Is it found in the shaded portion of the manometer by any chance? If so, why don't you make it easier for those persons that you are asking for help by pointing this out? Don't you think that you could possibly be helping your own self obtain help if you made it easier and clearer for your readers to fully understand and comprehend what your problem is, how much of your own problem you have tried to solve (and how), and what part is the part that you don't understand?

The best help you can obtain is probably in your own Static Fluid Mechanics text book (where this problem probably originated). Tell us the whole story: are you presently taking a course where you were assigned this problem? are you having problems understanding your professor or instructor? are you having problems understanding your text book? What text book are you studying? Have you studied other text books? Have you studied other sources in the Internet?

All these points mentioned above would be of help in helping you out. In the meantime, let me alert you to the fact that these Forums are not a free source for doing your own homework assignments. We will help you. We won't do your work for you. Send us the information to help you out.

From the information given, the unknown fluid is the shaded portion of the manometer.

I am confused as to how to solve this; do I treat each u bend in succession? I.e. from h1 to h2, h3 and so on?

I am currently a distance learning student who works full time. my student - teacher is very limited to say the least. I am currently working from Perrys Handbook for Chemical Engineers, C+ R Vol 1 And Fluid Mechanics: Worked examples for engineers. These texts do not contain the same problem as i am describing.

I have only found one other source of information that may be useful to me. I have attached this alongside this post (question 3.38E). It is similar however in my problem both openings are open to atmosphere, this example however has only one opening to atmosphere. I am still having problems however.

I understand what you are saying in your post. I shall endeavour to be more concise with the nature of my problems in the future.

Many thanks,
Sharon

[Art Montemayor]

Sharon:

Good reply to my query. Your re-definition is also the sort of query input that we need in order to be of maximum help - without hindering your learning abilities. It is important that you distinguish what type of problem this is, what tools are needed to resolve it, and what is the typical plan of attack in setting up your algorithm.

The typical way to set up the algorithms (there are several) is to start - as you have surmised - to resolve one section at a time. However, the sections are defined by the fluids in question - not by the "U" bends. The "U"bends are incidental. They mean little, if anything at all. The FLUID is the key because it represents the pressure source in statics. The fluid's density (or specific gravity, or relative density) is what leads you on to a solution of the ultimate pressure. And, as you have noted, you deal with each section in succession you will obtain a solution as you step-wise resolve each section.

Make a list of all your known basic data. Sometimes this can be given in a very subtle way. You know the fluids and their densities. You also should know (usually) the inlet and outlet pressures (or lack of pressure). The fluid heights (remember, this is STATICS and the fluid height determines the bottom pressure) are the next items that should be given or are required as answers. The equations in Static Fluid Mechanics are some of the most simple and easy to comprehend. However, you should have a good, detailed text book to learn by. Perry's Handbook is just that - a handbook for the professional engineer. It was never intended to be a text book for students and, as such, is very difficult for a student to learn basic engineering knowldege from it. I recommend you obtain a detailed text book. I don't know where you are located or what your facilities and infrastructure are or look like, so I can't recommend much more. (see what I mean about giving us as much background and details in order to help you?).

I am presently not at my residence, and away from my private library. I am with my grandchildren for Christmas and plan to spend the next week in LegoLand with them. Therefore, I can refer you specifically to any one book or literature immediately. However, there are still some very experienced and learned professional on this Forum that I am sure will come to your specific aid and assistance in learning how to start setting up the needed algorithms that will lead you to the answer.

Please note that the copy of the manual you submitted is limited to use ONLY by teachers. I don't know how you got the use of such a manual and I hope that it was LEGAL. You should not have any access to this manual according to the note on the document. If your teacher gave it to you, he/she did something wrong and is not teaching. If you obtained it through a student (who also shouldn't have it), then you are participating in an unethical act - and that is wrong. You don't need to slink around and use unethical and wrong methods to obtain learning and information regarding your self-improvement. Something is definitely wrong in the system if that is what you have to do to obtain, true, honest, and correct engineering instructions and teachings.

Have a Happy Christmas and a Prosperous New Year!

[sharon567]

Many thanks for your help on this Art you have yourself a enjoyable time over the holidays.

If anyone else could help with this problem i would really appreciate this.

Merry Christmas

Sharon

[djack77494]

Sharon,
You may note that your problem 3-38E is very similar to your own situation. You must start with atmospheric pressure at one of your two open ends. Now do hydrostatic calculations for each of three fluid segments to get to the second open end where your pressure is again atmospheric. In other words, start from the left side with P=atmospheric. As you go down the left leg, through the left U bend, and up to your first water-unknown interface, calculate a pressure in a manner just like your examples. Next add a term for the unknown fluid, and finally add a term for going from the right interface, through the right U bend and up to atmospheric pressure on the right side of the manometer. If I said any more, I'd have to finish with a "Merry Christmas".