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Medical Forum / Diseases and Disorders / Epilepsy / January 2004OT: physics puzzle
Howdy! I posted this on an "ask a stupid question" thread in another epilepsy forum. Let's see if our fellow scientists, teachers and other creative thinkers can come up with an answer: Start with a sealed submarine underwater... If you put a flying bird into the submarine does the weight of the submarine change? I'll give the answer that I came up with in a later post.  SignatureDave ???? "Noli illigitemi carborundum decendus" http://www.howdydave.com "Dave ©¿©¬" wrote: > Howdy! > [quoted text clipped - 7 lines] > > If you put a flying bird into the submarine How does a flying bird get into a sealed submarine underwater?<lol> > does the weight of the submarine > change? The weight of the submarine itself? or the weight of the submarine plus contents? > I'll give the answer that I came up with in a later post. I'd rather have a question first. :-) > Dave ©¿©¬ > "Noli illigitemi carborundum decendus" > > http://www.howdydave.com Non carborundum illegitemi. Bob > "Dave ©¿©¬" wrote: > [quoted text clipped - 21 lines] > > I'd rather have a question first. :-) Hey Dave! Where are you? I asked a question. :-) Bob Obviously, the submarine weighs more with the bird in it. This can be proved if the bird comes to rest on the floor - it would simply be another object. If flying, it would displace air, adding weight also. Jill > > "Dave ©¿©¬" wrote: > > [quoted text clipped - 27 lines] > > Bob Howdy! Oh... I forgot to say that the displaced air was removed from the sub. Answering Bob's question: Scotty beamed the bird into the sub and beamed the air displaced by the bird out of the sub. Since the sub is pressurized, the air turbulance caused by it's flapping wings would be evenly distributed in all directions, not just as an opposing force against the deck. In answer to Jill: Exactly IF THE BIRD CAME TO REST ON THE FLOOR; but it isn't on the floor, we're talking about the weight of the sub while the bird is in flight! We went on for more than 40 postings without coming to a definate decision. Weight is a function of mass and gravity. Since the bird is in the air, the gravity force has been negated. The mass has definately been increased, but we're talking about the weight, not the mass. Hmmm... curiser and curiser... SignatureDave ???? "Noli illigitemi carborundum decendus" http://www.howdydave.com > Obviously, the submarine weighs more with the bird in it. This can be > proved if the bird comes to rest on the floor - it would simply be [quoted text clipped - 30 lines] > > > > Bob Dave ©¿©¬ <dave@_nospam_howdydave.com> wrote >Since the sub is pressurized, the air turbulance caused by it's flapping >wings would be evenly distributed in all directions, not just as an opposing >force against the deck. IMHO it wouldn't (see bit about virtual column of air below). >In answer to Jill: >Exactly IF THE BIRD CAME TO REST ON THE FLOOR; but it isn't on the floor, >we're talking about the weight of the sub while the bird is in flight! It doesn't matter whether it's on the floor or flying, the weight will increase when the bird is added to the sub. Gravity has not been overcome if the bird is flying at a constant level : the downwards force (weight) equals the upwards force (upthrust) and is transferred downwards to the internal floor of the sub via the virtual column of air which its flapping wings produce (imagine standing under a hovering helicopter if you need an example of a virtual column of air). Interestingly, if the bird stops flapping and goes into a free-fall nose dive, the sub gets lighter. If it pulls itself out of its nose dive and decides to climb in order to loop the loop, the sub gets heavier. But then that would also happen if the captain decided to move around the ship on a pogo-stick as well. >We went on for more than 40 postings without coming to a definate decision. I'm not surprised, it's a nice meaty question requiring clear thinking. >Weight is a function of mass and gravity. Since the bird is in the air, the >gravity force has been negated. I disagree. The 'gravity force' has not been negated it has been balanced by an equal and opposite upthrust from the downblast of air. This air has to push against something, and that something is the bottom of the sub. Hence an increase in weight. >The mass has definately been increased, but we're talking about the weight, >not the mass. > >Hmmm... curiser and curiser... If you want another question.... Designing stair lights (turn on/off from top or bottom) with SPDT switches is easy from two places: . ____________ _______/ ____________ \____________ but can it be done from three? I *think* I've got the solution using a DPDT but maybe someone who's worked with these things can say "Easy, all you do is...". Looking forwards to your answers. It kept me up for ages last night drawing 3D truth tables for my attempts. SignatureMalcolm Howdy Malcom! Are we talking about upthrust or a constant pressure from beneath and a reduction of pressure on top (aerodynamics) does this mean being pushed up from beneath or being sucked up from above? SignatureDave ???? "Noli illigitemi carborundum decendus" http://www.howdydave.com > >Since the sub is pressurized, the air turbulance caused by it's flapping > >wings would be evenly distributed in all directions, not just as an opposing [quoted text clipped - 47 lines] > Looking forwards to your answers. It kept me up for ages last night > drawing 3D truth tables for my attempts. The key (I think) is "Instantanious measurement" SignatureDave ???? "Noli illigitemi carborundum decendus" http://www.howdydave.com > Howdy Malcom! > [quoted text clipped - 57 lines] > > Looking forwards to your answers. It kept me up for ages last night > > drawing 3D truth tables for my attempts. Dave ©¿©¬ <dave@_nospam_howdydave.com> wrote >Howdy Malcom! > >Are we talking about upthrust Upthrust is usually a term of hydrodynamics explaining why an object floats (force from below = weight of object , so a balanced object neither moving up nor down). >or a constant pressure from beneath and a >reduction of pressure on top (aerodynamics) does this mean being pushed up >from beneath or being sucked up from above? Pushing and sucking are both the same (tell that to your SO!). They are merely a force generated by the difference between lower pressure and upper pressure. When the pressure underneath is greater than the pressure on top it provides an upthrust. When this is equal to the bird's weight, the bird stays vertically immobile. If the pressure underneath *is* greater, it means that a vertical pressure differential has been created within the sub by the bird flapping, and this differential will push down more on the lower hull than the upper hull. Thus the weight of the bird is transferred to the hull, and the sub is heavier with the bird in it. But this doesn't tell me how to wire my landing/hall before the carpetmen come and seal the floorboards permanently. SignatureMalcolm Howdy Malcom! If you tell your SO that there's no difference between pushing and sucking, you won't get either for at least a month! What do you bet? Upthrust - here in the USA we call that bouyency! Is bouyency an international term or just used here in NA? I'm amazed -- I just looked in the index of my University Physics textbook and didn't find the word "bouyency" in there at all! Lots of difference between pushed up and sucked up (talking about physics here, not erotics!) We have to use differential calculus for one and integral calculus for the other (don't we?) SignatureDave ???? "Noli illigitemi carborundum decendus" http://www.howdydave.com Dave ©¿©¬ <dave@_nospam_howdydave.com> wrote >Upthrust - here in the USA we call that bouyency! Is bouyency an >international term or just used here in NA? I'm amazed -- I just looked in >the index of my University Physics textbook and didn't find the word >"bouyency" in there at all! sp = Buoyancy. >Lots of difference between pushed up and sucked up (talking about physics >here, not erotics!) We have to use differential calculus for one and >integral calculus for the other (don't we?) Calculus ? No. To avoid complicating matters with silly things like additional weight etc imagine a horizontal tube with a bullet-like plug inside it.... _____________________________________ X | | Y _______________|__|__________________ Assume atmospheric pressure is 10 N/cm^2. Plug face area of 5 cm^2. The force on both plug faces = P x A = 10 x 5 = 50 N. Both forces are equal so the plug does not move. Sucking at end X decreases pressure at X to 8 N/cm^2. The force on face X = 8 x 5 = 40 N. Resultant force = 40 - 50 = -10N so plug is *sucked* to the left. Blowing at end X increases pressure at X to 12 N/cm^2. The force on face X = 12 x 5 = 60N. Resultant force = 60 - 50 = 10N so the plug is *blown* to the right. ?????????????? No calculus of any kind there, is there ???????????? (Early in the morning so any typos are not my fault.) SignatureMalcolm Howdy malkum! I never could spel anywhey! The bullet analogy doesn't work because you have the outer atmosphere effecting the flow within the system. Oh well... I couldn't find anything in the index starting with bouy anyway! SignatureDave ???? "Noli illigitemi carborundum decendus" http://www.howdydave.com > >Upthrust - here in the USA we call that bouyency! Is bouyency an > >international term or just used here in NA? I'm amazed -- I just looked in [quoted text clipped - 34 lines] > > (Early in the morning so any typos are not my fault.) Dave ©¿©¬ <dave@_nospam_howdydave.com> wrote >Howdy malkum! > >I never could spel anywhey! > >The bullet analogy doesn't work because you have the outer atmosphere >effecting the flow within the system. Huh? >Oh well... I couldn't find anything in the index starting with bouy anyway! Your ISP probably removed the post and sent it to the porno- investigators. Your name is now on their blacklist. SignatureMalcolm > Your ISP probably removed the post and sent it to the porno- > investigators. Your name is now on their blacklist. Howdy Malcom! huh? SignatureDave ???? "Noli illigitemi carborundum decendus" http://www.howdydave.com Howdy M! Oh... now I get it. I was talking about the index in my physics book looking up bouyncee! SignatureDave ???? "Noli illigitemi carborundum decendus" http://www.howdydave.com > >Oh well... I couldn't find anything in the index starting with bouy anyway! > > Your ISP probably removed the post and sent it to the porno- > investigators. Your name is now on their blacklist. Does this help at all? I couldn't figure it out but maybe you can. :-) http://www.lightingfacts.com/Four%20way%20switches.html > But this doesn't tell me how to wire my landing/hall before the > carpetmen come and seal the floorboards permanently. >Does this help at all? I couldn't figure it out but maybe you can. :-) > >http://www.lightingfacts.com/Four%20way%20switches.html Thanks. I think their '4 way switches' are swap-over switches which connect input A to output a and input B to output b. When flipped they will connect A to b and B to a. SignatureMalcolm "> If you want another question.... Designing stair lights (turn on/off > from top or bottom) with SPDT switches is easy from two places: > . ____________ [quoted text clipped - 3 lines] > DPDT but maybe someone who's worked with these things can say "Easy, all > you do is...". G'day malcolm _____________ ___________ _______/ _____________X___________ \_______ This is the basic circuit for intermediate switching where the X denotes a two way switch or double pole double throw. pablo > Looking forwards to your answers. It kept me up for ages last night > drawing 3D truth tables for my attempts. >G'day malcolm > _____________ ___________ [quoted text clipped - 3 lines] >two way switch or double pole double throw. >pablo Surely a DPDT will have 2 inputs and 4 outputs ?... . ______________ _______/ ______________ : . : ______________ _______/ ______________ The circuit I came up with was: . ______________ . | \__________________ . ______(______________ : \ / | : \___ _______/ | : . L______________ : . | \__________________ . ______|______________ . . A B C Thunderstorm coming - gotta go. SignatureMalcolm >>Thunderstorm coming - gotta go. I knew I'd get it wrong if I didn't have time to check it: . ______________ \ . | \__________________ . ______(______________ : \ . / | | : \___ . ______/ | | : . | L__________ \: . | \__________________ . ______|______________ . . A B C SignatureMalcolm G'day m, that's the circuit i used for the intermediate switching in my house. i have a switch downstairs, a switch at the top of the back stairs and a switch at the top of the front stairs. the back of the switch has four holes, two wires in and two wires out. _____________ ___________ _______/ _____________X___________ \_______ Position 1 _____________ __ ___________ _______/ ____________ __ ___________ \_______ Position 2 pablo > >>Thunderstorm coming - gotta go. > > [quoted text clipped - 10 lines] > . > . A B C "Dave ©¿©¬" wrote: > Howdy! > > Oh... I forgot to say that the displaced air was removed from the sub. > Answering Bob's question: That wasn't my question and I took your original question as being a trick question. If you were just talking about the submarine itself or the submarine + contents, it would make a difference in the questions. > Scotty beamed the bird into the sub and beamed the air displaced by the bird > out of the sub. What if Scotty beamed 2 tons of lead into the sub? Would that matter? > Since the sub is pressurized, the air turbulance caused by it's flapping > wings would be evenly distributed in all directions, not just as an opposing [quoted text clipped - 5 lines] > > We went on for more than 40 postings without coming to a definate decision. Was everyone trying to answer the same question?<g> > Weight is a function of mass and gravity. Since the bird is in the air, the > gravity force has been negated. Huh? > The mass has definately been increased, but we're talking about the weight, > not the mass. What if the sub were in space orbiting the earth? > Hmmm... curiser and curiser... That's for sure! Bob > Dave ©¿©¬ "Noli illigitemi carborundum decendus" > [quoted text clipped - 42 lines] > > > > > > Bob It will weigh precisely the same!!! Why post this here? > Howdy! > [quoted text clipped - 16 lines] > > http://www.howdydave.com > It will weigh precisely the same!!! Why post this here? Because Dave lives here. Mary > > Howdy! > > [quoted text clipped - 18 lines] > > > > http://www.howdydave.com It will weigh more because the submarines weight will include everything inside it including the bird. It makes no differnece whether the bird is flying sitting etc. Or that what i think anyway Isabelle > It will weigh precisely the same!!! Why post this here? > > Howdy! [quoted text clipped - 19 lines] > > > > http://www.howdydave.com It'll way a hell of a lot more. All the water that gets in when you open the (sealed) hatch to put the bird in will give it a serious flotation problem. Signature------------------------------------------------------------------------- FIGHT BACK AGAINST SPAM! Download Spam Inspector, the Award Winning Anti-Spam Filter http://mail.giantcompany.com > It will weigh precisely the same!!! Why post this here? > > Howdy! [quoted text clipped - 19 lines] > > > > http://www.howdydave.com Spotted in an educational newsletter (and flawlessly scanned in by Textbridge)... Cold Day In Hell: The following is an actual question given on University of Washington chemistry mid-term exam. The answer by one student was so "profound" that the professor shared it. Bonus Question: Is Hell exothermic (gives off heat) or endothermic (absorbs heat)? Most of the students wrote proofs of their beliefs using Boyle's Law, (gas cools off when it expands and heats up when it is compressed) or some variant. One student, however, wrote the following: First, we need to know how the mass of Hell is changing in time. So we need to know the rate that souls are moving into Hell and the rate they are leaving. I think that we can safely assume that once a soul gets to Hell, it will not leave. Therefore, no souls are leaving. As for how many souls are entering Hell, let's look at the different religions that exist in the world today. Some of these religions state that if you are not a member of their religion, you will go to Hell. Since there are more than one of these religions and since people do not belong to more than one religion, we can project that all souls go to Hell. With birth and death rates as they are we can expect the number of souls in Hell to increase exponentially. Now, we look at the rate of change of the volume in Hell because Boyle's Law states that in order for the temperature and pressure in Hell to stay the same, the volume of Hell has to expand proportionately as souls are added. This gives two possibilities: 1. If Hell is expanding at a slower rate than the rate at which souls enter Hell, then the temperature and pressure in Hell will increase until all Hell breaks loose. 2. Of course, if Hell is expanding at a rate faster than the increase of souls in Hell, then the temperature and pressure will drop until Hell freezes over. So which is it? If we accept the postulate given to me by Ms. Teresa Banyan during my first year here, "... that it will be a cold day in Hell before I award you full marks." and take into account the fact that I still have not succeeded in obtaining full marks, then, number 2 cannot be true, and thus I am sure that Hell is exothermic and will not freeze. The student received the only "A". SignatureMalcolm Howdy Malcom! That sounds quite a bit like a psychology exam that I heard about... For 5 minutes everybody had to sit there with pen in hand and write down every thought that popped into their head. Upon reading the exams one of them contained entries like: This is stupid! Why the f*** is he making us do this? That's it, this is so stupid I'm not going to do it anymore! randomly throughout the list, and then went on it's way. The student who wrote that in his list was the only one to get an 'A'! SignatureDave ???? "Noli illigitemi carborundum decendus" http://www.howdydave.com > Spotted in an educational newsletter (and flawlessly scanned in by > Textbridge)... [quoted text clipped - 45 lines] > > The student received the only "A". That doesn't really get to the underlying question. Do I wear shorts/t-shirt or thermal underwear when I die? > Spotted in an educational newsletter (and flawlessly scanned in by > Textbridge)... [quoted text clipped - 45 lines] > > The student received the only "A". > That doesn't really get to the underlying question. Do I wear shorts/t-shirt > or thermal underwear when I die? I realise that you're asking a very profound question related to the Hell essay and I have no answer to that - you'll have to make a decision for yourself. Go on - you can do it if you try really hard. But despite all that you reminded me that the other day I asked Spouse what he'd like to wear to be buried in. We take part in period events so have kit in Roman, Viking, Norman, C15th, Georgian and Victorian/Edwardian so the question was relevant. He said his boiler suit. That's very fitting too, he spends more time in that than any other outfit, making and mending. It might be suitable for Hell too - not that he'll be going there unless he visits me. Mary Howdy Mary! re: I asked Spouse what he'd like to wear to be buried in. That's a tough one... you see, I'm a body donor. They will probably be disecting me in anatomy 101 (or something of the sort) at a medical school for 2 or 3 years. Once they have finished with me all of my clothes will be out of fashion! SignatureDave ???? "Noli illigitemi carborundum decendus" http://www.howdydave.com > Howdy Mary! > re: I asked Spouse what he'd like to wear to be buried in. [quoted text clipped - 8 lines] > "Noli illigitemi carborundum decendus" > http://www.howdydave.com * G: They're started ALREADY??! :-< ... "Cheap shots 2/ dollar" .... // > Howdy Mary! > [quoted text clipped - 3 lines] > disecting me in anatomy 101 (or something of the sort) at a medical school > for 2 or 3 years. So am I. But they probably won't want me now. > Once they have finished with me all of my clothes will be out of fashion! Will you still be clothed when they've finished with you? Mary >> Howdy Mary! >> [quoted text clipped - 5 lines] > >So am I. But they probably won't want me now. It makes sense for everyone on this NG with Ep to be a body donor because the more they can find out about our particular brains the better. Actually, with my memory problems, the more things *I* could find about my brain the better it would be for me - I forgot my bank PIN the other day and I've been using it since Cashpoints first came out in the Seventies! My MedicAlert contains the addendum: "All organs available for transplant or, if found unsuitable, for research." I doubt anything could be used for donation because they won't even take my blood anymore. But surely there's a place on the Net where I could sell other parts - (vgc, good handling, low mileage, one careful owner). Or maybe I should add an extra "or, if found unsuitable, for McDonalds." at the end? SignatureMalcolm > Or maybe I should add an extra "or, if found unsuitable, for McDonalds." > at the end? LOL! It won't matter to me, I never eat at McD's. Mary good question. what does today's downwardly mobile cadaver wear to fit in with the latest fashions? does christian dior have range which would be chic for these occasions? pablo > That doesn't really get to the underlying question. Do I wear shorts/t-shirt > or thermal underwear when I die? [quoted text clipped - 48 lines] > > > > The student received the only "A". > good question. what does today's downwardly mobile cadaver wear to fit in > with the latest fashions? does christian dior have range which would be > chic for these occasions? > pablo Pablo, Christian Dior has joined them. Mary >> good question. what does today's downwardly mobile cadaver wear to fit in >> with the latest fashions? does christian dior have range which would be >> chic for these occasions? >> pablo > >Pablo, Christian Dior has joined them. Well, what did _he_ wear then? SignatureMalcolm > >> good question. what does today's downwardly mobile cadaver wear to fit in > >> with the latest fashions? does christian dior have range which would be [quoted text clipped - 4 lines] > > Well, what did _he_ wear then? didn't you see it? A natty little black shroud, casket-line. Mary well now you know how up with today's latest fashions i am! pablo > > good question. what does today's downwardly mobile cadaver wear to fit in > > with the latest fashions? does christian dior have range which would be [quoted text clipped - 4 lines] > > Mary Howdy Pablo! Guess I'll just have to wear my old bib Levi's and you can wear whatever, eh? SignatureDave ???? "Noli illigitemi carborundum decendus" http://www.howdydave.com > well now you know how up with today's latest fashions i am! > pablo [quoted text clipped - 8 lines] > > > > Mary Dave ©¿©¬ <dave@_nospam_howdydave.com> wrote >Howdy Pablo! > >Guess I'll just have to wear my old bib Levi's and you can wear whatever, >eh? Nah. Be eco-friendly. Recycle your clothes at the local charity shop and be buried starkers. SignatureMalcolm > >Howdy Pablo! > > [quoted text clipped - 3 lines] > Nah. Be eco-friendly. Recycle your clothes at the local charity shop and > be buried starkers. That's what I plan - if the hospital doesn't want me. Most of my clothes come from the charity shops anyway, except those we make. g'day dave, so you think i should dig out the old flares and the paisley shirt? pablo > Howdy Pablo! > [quoted text clipped - 14 lines] > > > > > > Mary > g'day dave, > so you think i should dig out the old flares and the paisley shirt? > pablo Ooh yes! Send a picture :-) Remove the b. Mary Howdy Mary! Is it just my technical writer mindset (which usually is erroniously assumed to be perversion)... or is there a double/treble meaning buried somewhere within that "Remove the b."? (Should that be: Remove the ".b."? SignatureDave ???? "Noli illigitemi carborundum decendus" http://www.howdydave.com > > g'day dave, > > so you think i should dig out the old flares and the paisley shirt? [quoted text clipped - 5 lines] > > Mary > Howdy Mary! > > Is it just my technical writer mindset (which usually is erroniously assumed > to be perversion)... or is there a double/treble meaning buried somewhere > within that "Remove the b."? > (Should that be: Remove the ".b."? I've absolutely no idea what you're talking about :-) Unless it's that there's no point in replying to mary.b.fisher, I THINK it's mary.fisher ... Mary > > > g'day dave, > > > so you think i should dig out the old flares and the paisley shirt? [quoted text clipped - 5 lines] > > > > Mary >Spotted in an educational newsletter (and flawlessly scanned in by >Textbridge)... [quoted text clipped - 14 lines] > >The student received the only "A". And well he should have! There is nothing more precious among us then intellectuals with senses of humor....(especially when said humor exposes such a well grounded grasp of the arguments involved) ;-) My kinda guy! Or girl, whatever.... PS: I know the thread is dead after the few months here in existant. But I enjoyed it and answered anyway. Howdy Andrew! It was originally posted with an "OT" on the subject line. HOWEVER One thing to remember... with some of the drugs that a lot of us take for our epilepsy it is absolutely essential to get a little bit of exercise in order to prevent brain-rot from setting in! SignatureDave ???? "Noli illigitemi carborundum decendus" http://www.howdydave.com > It will weigh precisely the same!!! Why post this here? > > Howdy! [quoted text clipped - 19 lines] > > > > http://www.howdydave.com |
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