warren@amc.UUCP (Warren Omohundro) (04/07/88)
In an attempt to put the 'misc' back in 'sci.misc', I have an "ASK MR. SCIENCE" type of question. My family consumes a fair quantity of milk every week, and as a consequence, we are left with a number of those disgusting, gallon, plastic jugs. To salve our recycling conscience, the jugs are washed out and used for other things. (anybody want a bird feeder?) Washing the jugs consists of putting a small amount of detergent water into the jug, covering the mouth of the jug with a hand, and shaking vigorously. When you uncover the mouth of the jug, there is a noticable release in pressure. My question: Where does the extra air pressure come from? It must have something to do with the formation of the soap bubbles, since repeating the procedure with plain water generates no extra pressure. So what is going on?
crown@dukempd.UUCP (Rick Crownover) (04/08/88)
In article <631@amc.UUCP>, warren@amc.UUCP (Warren Omohundro) writes: > My family consumes a fair quantity of milk every week, and as a > consequence, we are left with a number of those disgusting, gallon, > plastic jugs. To salve our recycling conscience, the jugs are washed > out and used for other things. (anybody want a bird feeder?) Washing I know that in Oregon City, Oregon (and probably Portland also), those jugs are recycled right along with the metal cans and papers. I don't know what is done with them; but, maybe some friendly Oregonian out there can tell us. Then, we can spread the technology! I don't think milk is "soapy." Do you? Rick -- Rick Crownover 1-919-684-8279 Duke University Dept. of Physics crown@dukempd.uucp Durham, N.C. 27706 mcnc!duke!dukempd!crown
majka@anchor.cs.ubc.ca (Marc Majka) (04/08/88)
In article <631@amc.UUCP> warren@amc.UUCP (Warren Omohundro) writes: > Washing the jugs consists of putting a small amount of detergent water into > the jug, covering the mouth of the jug with a hand, and shaking vigorously. > When you uncover the mouth of the jug, there is a noticable release in > pressure. My question: Where does the extra air pressure come from? How about heat? When you begin, there is hot water and cool air in the jug. After shaking it around for a bit, the air will have heated and expanded. This is just my guess. Try a couple of experiments: 1: Use cold soapy water. 2: Use hot water and no soap. --- Marc Majka
wine@maui.cs.ucla.edu (David Wine) (04/09/88)
Do you perhaps use hot water with the soap? --David Wine University of California at Los Angeles wine@cs.ucla.edu Computer Science Department (213) 825-6010 3531 Boelter Hall Los Angeles, CA 90024
fmm@notecnirp.Princeton.EDU (F. Miller Maley) (04/09/88)
In article <631@amc.UUCP> warren@amc.UUCP (Warren Omohundro) writes: > Washing the jugs consists of putting a small amount of detergent > water into the jug, covering the mouth of the jug with a hand, and > shaking vigorously. When you uncover the mouth of the jug, there is > a noticable release in pressure. My question: Where does the extra > air pressure come from? > It must have something to do with the formation of the soap > bubbles, since repeating the procedure with plain water generates no > extra pressure. So what is going on? I think this is an easy one. If you use water that is hotter than room temperature, then shaking the jug causes the water in the jug to heat the air. Consequently, the pressure increases; the soap has nothing to do with it. Due to the narrow mouth of gallon milk jugs, most of the hot air will remain inside the jug when the soapy water is poured out. Hence repeated washings or rinsings will not produce nearly as great an effect. Try it with plain water first and see what happens. Also, try it with very cold water and see if you don't get the opposite effect. -- Miller Maley 609-987-2808 | ...!princeton!fmm | 3x10^5 km/sec. It's not just Princeton Computer Science | fmm@princeton.edu | a good idea. It's the law.
todd@uop.edu (Dr. Nethack) (04/13/88)
In article <631@amc.UUCP>, warren@amc.UUCP (Warren Omohundro) writes: > In an attempt to put the 'misc' back in 'sci.misc', I have an "ASK MR. > SCIENCE" type of question. > the jugs consists of putting a small amount of detergent water into > the jug, covering the mouth of the jug with a hand, and shaking > vigorously. When you uncover the mouth of the jug, there is a noticable > release in pressure. My question: Where does the extra air pressure come > from? It must have something to do with the formation of the soap > bubbles, since repeating the procedure with plain water generates no > extra pressure. So what is going on? This is an ancient mayan power beam passing through your milk carton by the resonant frequency of your hand, in more modern times it has been called "Orgone energy" Remember, Dr. Science has a master's degree.. in *Science* ;-) ----------------------------------------------------------------------- + uop!todd@uunet.uu.net + + cogent!uop!todd@lll-winken.arpa + + {backbone}!ucbvax!ucdavis!uop!todd + -----------------------------------------------------------------------
howell@ecsvax.UUCP (Doc A. Howell) (04/14/88)
How about this answer? When you have soap in the container with a certian amount of water it occupies an amount of space. When you shake the container the soap mixes with the water and expands which compresses the air inside of the jug. To test this theory, I guess you could fill a jug with soap suds, seal it tight and let it set until the suds settled back to basically just soapy water. When you removed the cap, there should be a rush of air back into the bottle. Another more scientific possibility would be that the soap could react with the water molecules and cause them to break up into their hydrogen and oxygen components. Since a gas is more active than a liquid the pressure would increase inside of the jug. I like both of these answers so take your pick.