In a closed glass tank which is filled with water to the brim, there are two spheres, one of cork and one of lead. The cork sphere is fixed to the bottom by a thread to prevent it from rising further; the lead sphere hangs from a thread fixed to the top of the tank. The lengths of the threads are such that the lead sphere is hanging just above the cork sphere. Explain what happens from the point of view relative to the tank and from the point of view relative to the Earth, if the tank is now suddenly moved to the right.

           __________________
          |        |         |
          |========|=========|
          |========|=========|
          |========|=========|
          |========O=========|  <----- lead sphere
          |==================|
          |========O=========|  <----- cork sphere
          |========|=========|
          |========|=========|
          |========|=========|
          |________|_________|

I think the reason sugar alone is so hard to mix by shaking is its density.  Sugar is just a little more dense than water so it wouldn't be affected much.

Cork is much less dense and lead is much more dense, so they would move a lot more.

Air is least dense an lets the water move around it a lot, this provides agitation to help the sugar dissolve.

 

Posted by Jer on 2006-01-10 12:46:03