Recovering Engineer

About air pressure: In all this , should air pressure be assumed as an upward force or a downward force? eg. when the can with one slit in it, is standing on the table, air pressure is pushing down on it - ? when the can (with just one slit in it) is being tilted downwards to try to pour, is air pressure pushing upwards onto the slit, stopping the juice from coming out?

pls check whether i'm understanding this or not. by upward force do you mean the air that has entered the can, helping to push the liquid out? so it's all clear enough now (i think) but am just curious.. is this scenario possible: a void being created in the can while it's being poured? ------------------------------------------------------------------------------------------------------------------------------------------------------------ Sorry for the change of name, it was a bad call but I cant change it back now. I've emerged from illness with a mushy mind. But to be honest I dont know if I understood this stuff even pre-insanity days.

Okay now Im wondering - why is the air so powerful, when liquid is so much denser? Even if it's the liquid in one can of juice vs. all the air in the room, still, theres space between each air molecule, how come the liquid molecules can't displace those spaces? Also, now I'm also wondering about how, for instance, scuba divers can enter a submerged ship / underwater station without taking all the water in the ocean with them into the ship. How do you build up enough air pressure in a single vessel, however big it might be, to match the water pressure of the entire ocean.? To ewmon: About the tiny window - which started this whole thread - I think I will actually install a fan in the window now. Thanks for this!!! I neglected to mention the room has a high ceiling, and someone also suggested that making a small hole, at least 8x8 inches, near the ceiling, would help let the hot air out because otherwise, the hot air that has risen to the top has no way to go but down into the room again. I think it makes sense, but do you reckon this would make a difference?

So if I waited a while (to let some air in) before pouring the liquid, would a single slit work even if the slit is fully covered with liquid? (sorry, im confused)

Hi there, I have a question about opening a can of juice (for instance, pineapple juice) by puncturing the top end on with a knife. While I think I can guess why you have to make 2 holes on opposite sides of the lid, instead of just one (because two holes will allow opposing air & liquid / current flows, create an imbalance, finally pushing the juice out... 1) what exactly happens ? 2) how come making, for instance, two inch-long slits side by side on the lid, works too? Wouldn't the juice be coming up against air pressure pushing down in almost exactly the same direction? How come this works but having just one single ridiculous looking 2-inch slit will never let the juice out? 3) I'm asking this in relation to a room in our house that has a 2-ft wide x 2.5ft high window. It feels as though no air comes through the window, no matter the season. I am wondering whether, just like with the juice can, instead of the 2-ft window, they should have made two side by side 1-ft wide windows instead? Would that have created more flow?(The other 3 walls lead to other rooms so no chance for extra windows there).

So the CASM is not actually the most prestigious mathematics exam in the world (contrary to what Cambridge Univ states?)

Hi there, wondered if anyone here has ever taken the CASM , i have been curious about it and have some general questions about it - 1) How many exams does it actually comprise. From the website I am not sure whether it is : a)a series of exams to be taken in a span of 2 years. OR B) a 2-year seminar that ends in one huge exam. 2) Is it pronounced C.A.S.M. or pronounced to sound like "chasm"? Any help would be appreciated. Thanks in advance!

I was in the same position when I graduated from Electrical Engineering! When I graduated most of the job offers came from mobile phone companies and computer chip makers AND they were either managerial / sales jobs. I've realised since that engineering will just never be "scientific enough" as it doesn't ask the deep questions - only the surface ones - that is , it seeks to apply scientific concepts, not question the concepts themselves. My main interests are in physics and art & design and if I could do it all over I would have either 1) studied physics to PhD level - my great passion 2) studied industrial engineering (your subject) and done further studies in 3D design (designing - machines, commercial products, factories) My advice would be :look at the recruitment ads in the back of scientific/research journals that you love - if there is a job there that you want, then ake note of the degrees that they require of their candidates and take it from there.

I think I'm realizing from all this that it is healthier to go jogging in the morning (more O2) than in the evening....

I know this is crude, but I am really curious as to how these things are measured so here goes: How many trees would one person need in a year to have enough oxygen to live? That is: Picture a very basic version of Biosphere 2, all complete except there is no oxygen / no oxygen source. Pretend Biosphere 2 is only 10 sq m big. What is the MINIMUM number of plants one person would need to have enough oxygen for a year? - or what is the volume of oxygen an individual consumes per year, and what is the volume of plants that could supply this oxygen? Wait a minute...how would the bodies of water form in Biosphere 2 the first place.... Im sure somebody out there can sort this out.......

How exactly does CO2 help you sleep? Is it the same principle as CO poisoning making you sleep ...to death? 1) Do plants release pretty much the same amount of CO2 day or night (respiration on same level all day long?) OR 2) Do they respire more during photosynthesis, thus releasing more CO2 in the day (although this is compensated by a lot of O2 release) and releasing less CO2 in the night (with no O2 release to compensate the CO2)

Thank you! I think your replies combined, answer my question. Rereading the quote "and [thus] can be reservoirs for quite a bit of the CO2 that's in the atmosphere," I guess the guy meant, reservoirs contained inside the grass, not in the atmosphere itself. That was the part that confused me. A new question though - regarding plants releasing CO2 all the time - does this mean esp at night and that , for instance, people who keep plants in their room should try to stay away from them at night cos they are slightly poisonous then? Thanks again for your help! cheers

Hi everyone. I have a few questions and would appreciate your help. I was never any good at biology in school so ... these might be stupid questions. sorry... 1) I was in the park one day and overheard a lady say "Not many people know that plants release oxygen only in the morning. By late afternoon, they release a lot of CO2". >>>>>>>>How true is this? 2) An article on TheScientist.com http://www.the-scientist.com/blog/display/57668/ mentioned that savannnas release a lot of carbon in to the atmosphere, and therefore, they are important. My question is, a. How do savannas release a lot of carbon - is this what the lady in the park meant? b. Now that everyone is anxious to reduce their "carbon footprint" how is it a good thing that savannas release a lot of carbon? c. Can this carbon actually be captured and harnessed for fuel? Here's the sentence: "Furthermore, "[savannas] are able to store and release a tremendous amount of carbon, and [thus] can be reservoirs for quite a bit of the CO2 that's in the atmosphere," he said "If we were to lose them, the ability to store carbon in this landmass goes away." Thankyou for bearing with me.