ENGINEERING.com Student Questions
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Student Questionsen-USActiveForums 4.2Copyright 2000-2013 ENGINEERING.comWed, 03 Dec 2014 10:26:11 GMTplease help me, big problemA counterflow double-pipe heat exchanger is currenily used to heat 2.5 kg/s of water from 25°C to 65°C by cooling an oil [cp = 2.2 kj/(kg K)| from 150°C to 95°C. It is desired to 'bleed off' 0.6 kg/s of water at 45°C so that the single exchanger will be replaced by a two-exchanger arrangement which will permit this. The overall heat transfer coefficient is 400 W/(m2 K) for the single exchanger and may be taken as this same value for each of the two smaller exchangers. The same oil flow is used for the two-exchanger arrangement, except that the flow is split between the two exchangers. Determine the areas of each of the smaller exchangers and the oil flow through each. Assume that the water flows in series through the two exchangers with the bleed-off taking place between them. Assume that the two smaller exchangers have the same areas. Take cp,water 4180 J/(kg K). <br /> <br /> please help me in solving this..i have tried my best and i have wasted 4 hours on it..plese any expert help me
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Ijaz AliWed, 03 Dec 2014 10:26:11 GMThttp://www.engineering.com/AskForum/aff/32/aft/1743/afv/topic.aspx0PLTW Principles of Engineering InterviewI am a highschool engineering student in need of an engineer to answer the following questions. Please answer as soon as possible and thanks in advance. <br /> <br /> QUESTIONS: <br /> <br /> a. Interviewee name: <br /> b. Interviewee’s specific degree: <br /> c. Interviewee’s place of employment: <br /> d. Interviewee’s email address and/or phone: <br /> <br /> • Please describe your engineering field. <br /> <br /> • What is your current job title? <br /> <br /> • Please describe your particular job and duties. <br /> <br /> • What is your average work schedule? <br /> <br /> • Starting with high school, describe your educational background chronologically. <br /> <br /> • If you had it to do over, related to your career or education, would you do anything differently? <br /> <br /> • What advice would you give to me as someone interested in pursuing a career path similar to yours? <br />
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Lucas HomcoTue, 02 Sep 2014 05:11:05 GMThttp://www.engineering.com/AskForum/aff/32/aft/1633/afv/topic.aspx1Engineering for over 30Hi, <br /> I could really use some help in choosing a field of engineering to study. I was wondering what would be the best field of engineering to study if you when you graduate you will be 35 yrs old. I am getting started rather late in life and would to choose a field where that won't hamper me very much. Please keep in mind that I am single and will be so for quite a while (although I am not sure if that matters or not). I was originally thinking of chemical or electrical engineering but any advice would be helpful.
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Cory mThu, 20 Nov 2014 15:30:55 GMThttp://www.engineering.com/AskForum/aff/32/aft/1730/afv/topic.aspx2computerengineering is a successful work
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fawas olamideMon, 01 Dec 2014 09:17:44 GMThttp://www.engineering.com/AskForum/aff/32/aft/1740/afv/topic.aspx0Student in need of engineering interviewI'm a high school student in an engineering course who needs to interview an engineer. Can someone fill this out for me please? <br /> <br /> Interviewee name: <br /> Interviewee’s specific degree: <br /> Interviewee’s place of employment: <br /> Interviewee’s email address and/or phone: <br /> <br /> Please describe your engineering field. <br /> <br /> What is your current job title? <br /> <br /> Please describe your particular job and duties. <br /> <br /> What is your average work schedule? <br /> <br /> Starting with high school, describe your educational background chronologically. <br /> <br /> If you had it to do over, related to your career or education, would you do anything differently? <br /> <br /> What advice would you give to me as someone interested in pursuing a career path similar to yours?
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Eric MeiSun, 28 Sep 2014 08:07:37 GMThttp://www.engineering.com/AskForum/aff/32/aft/1668/afv/topic.aspx1Aerodynamics potential flow analysisHi! I have an assignment on potential flow analysis. Could someone please help me with the 1st question I'm really struggling! Here it is: <br /> <br /> Topical Cyclone Hudhud, combined with a North easterly wind (120mph). Assuming the cyclone could be represented by an it rotational vortex, which could be represented by the steam function: ψ=(-K/2π)lnr <br /> And the potential function: φ=(-K/2π)θ <br /> <br /> 1. Derive expressions for the stream and potential functions of the combined flow. <br /> 2. What is the velocity field of the combined flow? <br /> <br /> <br /> ( The lecture told us that we needed to add the stream functions to give <br /> ψ=-urcosθ+Vrsinθ+(-K/2π)lnr ) <br /> Q1 needs to include polar co-ordinates <br /> <br /> Thanks!!! :D
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Hannah JaneThu, 20 Nov 2014 04:31:49 GMThttp://www.engineering.com/AskForum/aff/32/aft/1729/afv/topic.aspx0Major Research ProjectHi Everyone <br /> I'm about to embark on the required research project for the Masters degree. I have a few ideas of what I can do but would like to know if you can perhaps advise me on other possible ideas for a topic. <br /> I'm working in underground mining. <br /> Would prefer to do research that may have potential added value to mining in general. <br /> I know that efficiencies and greater productivity is a hot topic at this stage but not sure what I can do here. <br /> I'll appreciate any comment from those that may have been in a similar situation before. <br /> <br /> Thanks
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Johan van BlerkSat, 15 Nov 2014 16:51:55 GMThttp://www.engineering.com/AskForum/aff/32/aft/1724/afv/topic.aspx0Project for a ClassCan someone answer my interview questions? View All <br /> I was wondering if anyone wanted to be interviewed. It's for a Principles of Engineering class that I am taking, part of PLTW. I'm supposed to just interview a random engineer and thought maybe someone here could help. The answers don't have to be very long. <br /> <br /> Backround information: <br /> <br /> 1. What is your name? <br /> 2. What is your specific degree? <br /> 3. What is your place of employment? <br /> 4. What is your email address and/or phone number? <br /> <br /> Actual interview questions <br /> <br /> 1. Please describe your engineering field. <br /> 2. What is your current job title? <br /> 3. Please describe your particular job and duties. <br /> 4. What is your average work schedule? <br /> 5. Starting with high school, describe your educational background chronologically. <br /> 6. If you had to do it over, related to your career or education, would you do anything differently? <br /> 7. What advice would you give to me as someone interested in pursuing a career path similar to yours?
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John ElliottSat, 18 Oct 2014 17:59:11 GMThttp://www.engineering.com/AskForum/aff/32/aft/1688/afv/topic.aspx1Block Diagram and Transfer functionHi everyone, <br /> <br /> First I need to say that it is not an homework. This is an exercise. <br /> <br /> I need to find 2 transfer function from a block diagram, but I can't find answer b). But I know how to go from b) to c). <br /> <br /> Here is my problem statement (this is a translation from french): <br /> <br /> We want to know position x(t) of mass m with the help of a DC moteur and a gear system. All system elements are shown on picture 2. <br /> <br /> a) With the use of block diagram (first picture I posted) and parameters (in my last picture), find transfer function of every system elements. Consider initial condition to zero. <br /> <br /> b) Simplify the block diagram found in (a) to obtain the transfer function between the power supply of the motor and the speed of rotation of its shaft. <br /> <br /> c) From the transfer functions found in (b), find one that connects the motor electric supply to the displacement of the mass x (t). Determine the order of the system. <br /> <br /> And here is 3 picture to help solve my problem: <br /> <br /> http://s2.postimg.org/y8ve80duh/motor.png <br /> <br /> http://s1.postimg.org/xe4ihw7fz/transferfunction.png <br /> <br /> http://s2.postimg.org/y8ve80duh/motor.png <br /> <br /> Thank you very much. I have an exam monday! <br /> <br /> JP <br /> <br /> <br />
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Jean Philippe GuerinThu, 16 Oct 2014 03:22:28 GMThttp://www.engineering.com/AskForum/aff/32/aft/1687/afv/topic.aspx0Alternator for a coal-fired generatorI am doing a project on coal fired generator and I don't really know how my Alternator will work. I'm currently trying to use a 2 pole stator, 5 former making 1 pole, single phase alternator. <br /> These are the problems : <br /> how do I calculate/obtain the power rating of my alternator/generator <br /> does the Alternator work like the dynamo that generate voltage proportional to the rpm <br /> does a 50Hz alternator operate at 3000rpm to generate 240v <br /> relationship between torque, rpm and voltage
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Ayodele OkunadeWed, 15 Oct 2014 21:04:59 GMThttp://www.engineering.com/AskForum/aff/32/aft/1686/afv/topic.aspx0Should I become an engineer?I am currently picking classes for college and I am figuring if I should become an engineer. I feel like I would fail or not be the best in engineering because I am not the all-star at math. I was very good in physics but in Calculus I had trouble. My counselors suggest that I should go into mechanical engineering technology or some other variation. I was reading about it and I do not like the idea of just improving others ideas. Should I become an engineer?
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Steven ChanFri, 28 Jun 2013 04:02:22 GMThttp://www.engineering.com/AskForum/aff/32/aft/1051/afv/topic.aspx3Thermistor questionHello all, I am new to the site. I am an HVAC Professional, I own my business and I trying to find a way to use a thermistor as a simple relay for a 24 volt ac circuit. The goal is to have a thermistor that would allow the 24 volt ac voltage pass through when a specific temperature is reached. For example, the voltage circuit would be open until the temp reached 35 degrees, the thermistor would then close the circuit and would stay closed at any temp higher than 35, I have seen this done in an example video on you tube showing a light being turned on when the thermistor is heated with a blow dryer. Please let me know if you can help with the exact type of thermistor and specs related to it. thank you
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Lathan BainTue, 09 Sep 2014 13:52:05 GMThttp://www.engineering.com/AskForum/aff/32/aft/1642/afv/topic.aspx0Can't figure out Engineering SpecialtyI have been attending a Community College for the past year under the assumption that the program they have me listed under was for a pre-engineering degree where I would transfer elsewhere to finish. However, one year into it, I was just informed by one of my professors that the school has had me in the Engineering Tech program, and not the pre-engineering one. Now that the situation has been brought to my attention I have been looking at the class lists at my school for both degrees as well as the class list of the school I had been planning on transferring to. Neither look very promising and the more research I do, neither seem to be going in the direction I would like to take. <br /> <br /> I really would love to get into renewable/sustainable energy and the engineering to all involved. Solar, wind, and so on and so forth. However neither school even mentions any classes that include any of that or even have very many specializations for engineering at all. In my current class we are digging into the many types of engineers, however once again, very little is said on the green energy types other that being mentioned briefly as a type of engineering energy that is fast becoming popular... duh. <br /> <br /> I guess deep down I am crying out for help of any kind as to the direction I should be going. Are there any specific branches that include these kinds of engineering as an underlying topic that noone talks about? Is there a better way to specialize to bridge over and get into those areas? Mechanical versus civil versus economical engineering? Or is it a little bit of all of the above?
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P.ClairTue, 03 Jun 2014 18:04:55 GMThttp://www.engineering.com/AskForum/aff/32/aft/1309/afv/topic.aspx2mathshow to find the roots of eqn.....1+5/2 z^-1+2 z^-2+2 z^-3.
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aditi shahFri, 11 Apr 2014 12:21:56 GMThttp://www.engineering.com/AskForum/aff/32/aft/1271/afv/topic.aspx1gearbox calculationI am not an engineer. I am a mechanic by trade. So forgive me if this question is stupid or unreasonable. I have an idea... And invention I would like to try and build... And if such a thing was possible... It could literally change the world. <br /> <br /> Is it possible to design a gear box or a transmission in which the input to the transmission was 700rpm max @215 ft/lbs of torque and the output being at or very close to 3600rpm @ 35 ft/lbs of torque. <br /> <br /> I have literally no knowledge on how to figure something like this out or where to find answers. Its just a crazy idea I came up with... And f designing a transmission such as this was possible... My invention could actually work. And without saying what it is... It something that I cannot believe a guy like me could invent. And idea you would've expected someone would have already thought of and tried to make work. Anyways... Let me hear any POSITIVE input anyone has to say.
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Joshua boisWed, 11 Jun 2014 18:20:06 GMThttp://www.engineering.com/AskForum/aff/32/aft/1318/afv/topic.aspx2Is bending stress dependent on non-localized thickness?I had a disagreement with another engineer if bending stress in a certain location is affected by varying the thickness that is far from where the bending stress is to be calculated. <br /> <br /> Consider a simply supported beam with a concentrated load in the center. As far as I know, the shear and bending moment diagrams have nothing to do with the thickness of the beam. The center of the beam always has a bending moment of WL/4 regardless if the beam is thin in some parts and thick in other parts. Therefore if you have a known cross section in the center of say 1"X1", the bending stress could easily be calculated my finding the moment of inertia, and using the formula stress = My/I. That stress in that center cross section never changes even if the thickness in a different cross section changes. If the thickness in a different cross section was changed, the deflection in the center would change, but not the bending stress. <br /> <br /> The other engineer I was discussing this was saying that if the thickness somewhere between the supports and the center of the beam were made thinner, the center would deflect more. This I agree with. And he says that because it deflects more there is a greater curvature on the top surface of the beam and therefore the bending stress is greater at the center. This seems to contradict the equations described in the previous paragraph. <br /> <br /> Can someone tell me who is correct?
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Mike BTue, 05 Aug 2014 13:01:16 GMThttp://www.engineering.com/AskForum/aff/32/aft/1596/afv/topic.aspx1Statics questionIt's a beam suspended by a rope, like a drawbridge. 286,000 lbs seems a bit excessive, I think I might be doing something wrong.
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Dennis NedryWed, 06 Aug 2014 08:21:43 GMThttp://www.engineering.com/AskForum/aff/32/aft/1599/afv/topic.aspx1Engineer Interview<br /> a. Interviewee name: <br /> <br /> b. Interviewee’s specific degree: <br /> <br /> c. Interviewee’s place of employment: <br /> <br /> d. Interviewee’s email address: <br /> <br /> <br /> · Please describe your engineering field. <br /> <br /> <br /> <br /> · What is your current job title? <br /> <br /> <br /> <br /> · Please describe your particular job and duties. <br /> <br /> <br /> <br /> · What is your average work schedule? <br /> <br /> <br /> <br /> · Starting with high school, describe your educational background chronologically. <br /> <br /> <br /> <br /> · If you had it to do over, related to your career or education, would you do anything differently? <br /> <br /> <br /> <br /> · What advice would you give to me as someone interested in pursuing a career path similar to yours? <br /> <br /> <br />
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Jeffrey GammonWed, 20 Aug 2014 05:22:14 GMThttp://www.engineering.com/AskForum/aff/32/aft/1615/afv/topic.aspx0moment of Inertia for Rectangular steel tube with a flat bar welded on tubeHello, <br /> <br /> I am trying to find the new moment of inertia total for a rectangular stainless steel 4"x2"x.25"thk with a 3"x.75" flat bar welded on top of the short side of the rectangular tube. The short side (.75") of the flat bar will be welded to the center of the rectangular tube to the 2" side, total height of 7". I am looking for the moment of inertia at the x-x axis. I get a new moment of inertia total of 22.15 in^4. Can anyone confirm that the total is correct? i have a pdf of the calcs but it doesn't let me attach the file to the question.
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JOHN SAENZTue, 01 Jul 2014 09:43:57 GMThttp://www.engineering.com/AskForum/aff/32/aft/1540/afv/topic.aspx1Mechanical-biomedical engineeringHello, <br /> I am interested in pursuing a degree in mechanical engineering, and later, obtain a graduate degree in biomedical engineering. I would like to know what kind of jobs I can perform if I follow the mechanical-biomedical engineering route. How do these two field interact with each other? I love biology and I would love to work in medicine. <br /> Thanks for all the help you can provide. <br /> Maria
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Maria ArteagaFri, 04 Jul 2014 13:49:58 GMThttp://www.engineering.com/AskForum/aff/32/aft/1553/afv/topic.aspx0