Notices
Results 1 to 18 of 18

Thread: one question i dare not ask my teacher not to look stupid

  1. #1 one question i dare not ask my teacher not to look stupid 
    Suspended
    Join Date
    Jun 2009
    Posts
    893
    while not to buiold a huge one of this one to get energy from?



    Reply With Quote  
     

  2.  
     

  3. #2  
    Suspended
    Join Date
    Apr 2007
    Location
    Pennsylvania
    Posts
    8,795
    Drinking bird - Wikipedia, the free encyclopedia
    The ultimate source of energy is the temperature gradient between the toy's head and base; the toy is not a perpetual motion machine.


    Reply With Quote  
     

  4. #3  
    Brassica oleracea Strange's Avatar
    Join Date
    Oct 2011
    Location
    喫茶店
    Posts
    16,963
    Also it requires a supply of water. It would take more energy to keep it supplied than you could extract from it. (I doubt you could extract any useful amount of energy, anyway.)
    ei incumbit probatio qui dicit, non qui negat
    Reply With Quote  
     

  5. #4  
    Suspended
    Join Date
    Jun 2009
    Posts
    893
    Quote Originally Posted by Harold14370 View Post
    Drinking bird - Wikipedia, the free encyclopedia
    The ultimate source of energy is the temperature gradient between the toy's head and base; the toy is not a perpetual motion machine.
    yeah who said pp

    it only works as the sun causes evaporation at normal temp
    Reply With Quote  
     

  6. #5  
    Suspended
    Join Date
    Jun 2009
    Posts
    893
    Dunking bird of the second kind

    A 'dunking bird of the second kind' was introduced [3], which, while similar to the original drinking bird, will operate without a temperature difference, instead extracting free energy directly from the evaporation of water.
    Such a bird works as follows: It is balanced such that, when dry, it tips into a head down position. The bird is placed next to a water source such that this position brings its beak into contact with water. Water is then lifted into the beak by capillary action (the authors used a triangular sponge) and carried past the fulcrum. When enough water has been raised, the bird tips into a head up position. With the beak out of the water, eventually enough water evaporates from the sponge for the head to tip down again.
    Reply With Quote  
     

  7. #6  
    Forum Ph.D.
    Join Date
    Jan 2012
    Posts
    897
    Quote Originally Posted by luxtpm View Post
    Dunking bird of the second kind

    A 'dunking bird of the second kind' was introduced [3], which, while similar to the original drinking bird, will operate without a temperature difference, instead extracting free energy directly from the evaporation of water.
    Such a bird works as follows: It is balanced such that, when dry, it tips into a head down position. The bird is placed next to a water source such that this position brings its beak into contact with water. Water is then lifted into the beak by capillary action (the authors used a triangular sponge) and carried past the fulcrum. When enough water has been raised, the bird tips into a head up position. With the beak out of the water, eventually enough water evaporates from the sponge for the head to tip down again.
    lovely .....
    Reply With Quote  
     

  8. #7  
    Suspended
    Join Date
    Feb 2012
    Location
    Indiana. Near Indy. On the top of the Eastern "buttcheek."
    Posts
    183
    Most pp machines fail when a load is applied. PP is generally defined as motion requiring nothing to feed it, thus impossible. ONe may create a Virtual PP device, meaning it requires something to feed it, such as water.
    Reply With Quote  
     

  9. #8  
    Forum Ph.D.
    Join Date
    Jan 2012
    Posts
    897
    yeah sadly, but on the other hand, isn't that the concept of our universe?

    something staying consistant due to its surrounding?
    Reply With Quote  
     

  10. #9  
    Professor of Articulation Zesterer's Avatar
    Join Date
    Nov 2011
    Location
    The fourth dimension, our universe, the milkyway, outer galactic spiral 8, the solar system, earth.
    Posts
    43
    Look up entropy and the laws of thermo dynamics and you will see how they relate to this concept.
    Science cannot solve the ultimate mystery of nature. And that is because, in the last analysis, we ourselves are a part of the mystery that we are trying to solve.
    Max Planck
    Reply With Quote  
     

  11. #10  
    Forum Ph.D.
    Join Date
    Jan 2012
    Posts
    897
    i didn't question it, i just asked for agreement.
    Reply With Quote  
     

  12. #11  
    Comet Dust Collector Moderator
    Join Date
    Mar 2011
    Location
    New Jersey, USA
    Posts
    2,848
    And yet you asked it here.

    And 18 years of university was not enough, you're still there?
    Reply With Quote  
     

  13. #12  
    Forum Ph.D.
    Join Date
    Jan 2012
    Posts
    897
    what you mean?

    i didn't start this thread.
    Reply With Quote  
     

  14. #13  
    Suspended
    Join Date
    Jun 2009
    Posts
    893
    oh come on this is not pm just tapping sun energy efectivily

    hey buts lets contaminate all the water of the planet planet let everybody die b and take advnatgae of it

    thats the only reason they dont do thing s like this
    Reply With Quote  
     

  15. #14  
    Comet Dust Collector Moderator
    Join Date
    Mar 2011
    Location
    New Jersey, USA
    Posts
    2,848
    Quote Originally Posted by curious mind View Post
    what you mean?

    i didn't start this thread.
    Sorry, that reply was to the original post. for some reason (probably some kind of glitch), I could not see there were replies already, so did not include a quote. It was not directed at you, cm..
    Reply With Quote  
     

  16. #15  
    Moderator Moderator
    Join Date
    Jun 2005
    Posts
    1,620
    So, returning to the OP. It is by no means a stupid question - I say this because I asked a somewhat similar question in a physics class at school. Like....

    Suppose a perfectly dry jute rope of sufficient diameter is suspended over a lake in such a way that the lowest point just dips into the water. Then by capillarity, the entire rope gets wet, and thus contracts, thereby lifting the rope out of the water.

    As it drys, the rope expands, and again dips into the water, and the cycle continues ad infinitum.

    So, all credit to my teacher, he gave me a starter and invited me to go away and calculate the efficiency of this method of extracting energy from the sun. Needless to say, at 14 or 15 I wasn't able to do it, but was able to show it was extremely inefficient.

    On reading this, my teacher then asked the class to come up with a more efficient way of harvesting solar energy in a useful way. Some smart-arse (not me) had a good answer - chop down a tree and burn it.

    PS In those days we were not concerned particularly about so-called "green" energy production.

    PPS Never EVER be afraid to ask a question in class (or anywhere else) that you fear might be seen as stupid. Chances are, most other class members will be grateful for the resulting clarification from your teacher
    Reply With Quote  
     

  17. #16  
    Brassica oleracea Strange's Avatar
    Join Date
    Oct 2011
    Location
    喫茶店
    Posts
    16,963
    Quote Originally Posted by luxtpm View Post
    oh come on this is not pm just tapping sun energy efectivily
    I have doubts about "effectively". We already have other ways of using solar energy and I'm willing to bet that they are much more efficient than this could ever be.
    ei incumbit probatio qui dicit, non qui negat
    Reply With Quote  
     

  18. #17  
    Suspended
    Join Date
    Jun 2009
    Posts
    893
    Water evaporates at the rate of two liters per hour per one square meter of surface


    taking into account tallest trees are 130m you could rise 2 kg of water 65 m and let them make work by gravity every hour


    so you would have 2*65*10= 1300 jules per hour or 0.36w 24-7
    Reply With Quote  
     

  19. #18  
    Suspended
    Join Date
    Jun 2009
    Posts
    893
    The Minto wheel is a heat engine developed by Wally Minto.
    The engine consists of a set of sealed chambers arranged in a circle, with each chamber connected to the chamber opposite it. One chamber in each connected pair is filled with a liquid with a low boiling point (propane and R-12 are listed in the Mother Earth News articles). As the lower chamber in each pair is heated, the liquid begins to vaporize, forcing the remaining liquid to travel to the upper chamber. This fluid transfer causes a weight imbalance, which causes the wheel to rotate. Minto's pamphlet also suggests obtaining a pressure differential with a dissolved gas instead of a boiling gas. Soda water or propane dissolved in kerosene are suggested.
    The Minto wheel operates on a small temperature gradient, and produces a large amount of torque, but at very low rotational speed. The speed of rotation is directly proportional to the surface area of the containers used, the volume, and the height of the wheel. The higher the ratio of surface area to volume, the greater the rate of revolution.
    A working example of a wheel was first published in a series of articles in The Mother Earth News, Issues #38 March, #39 May and #40 July 1976.
    Test units constructed by Mother Earth News (Issue 40, July 1976) and the MythBusters (Episode 24, December 5, 2004 – "Ming Dynasty Astronaut") did work to convert temperature difference into torque; however not as well as overenthusiastic boosters claimed.[citation needed]
    [edit]See also

    Reply With Quote  
     

Similar Threads

  1. a stupid question?
    By geordief in forum Physics
    Replies: 13
    Last Post: March 6th, 2009, 04:01 AM
  2. Stupid Space Question
    By Brokenazs in forum Astronomy & Cosmology
    Replies: 17
    Last Post: January 12th, 2009, 11:28 AM
  3. A Stupid Question
    By georginho_juventusygr in forum Chemistry
    Replies: 2
    Last Post: March 27th, 2008, 06:32 AM
  4. Ask a stupid question...
    By eternal in forum Philosophy
    Replies: 89
    Last Post: July 28th, 2006, 05:37 AM
  5. A very stupid question
    By BraveBen in forum Physics
    Replies: 3
    Last Post: July 7th, 2006, 02:19 AM
Bookmarks
Bookmarks
Posting Permissions
  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •