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Physics - Newtonian Mechanics

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  • bonkysleuth's Avatar
    314 posts since Mar '07
    • Why is a glass that is filled with liquid less stable than an empty glass?

       

      I think this can be explained by the "lesser base area" theory. Can anyone help me elaborate or correct me if I'm wrong? Or do I explain in terms of te centre of gravity theory??

  • FirePig's Avatar
    1,183 posts since Mar '08
    • centre of gravity is higher on a glass filled with water. When the wind blows, the glass only needs to tilt a little and the whole structure will fall. Think of it like stacking uno stacko.

  • 4794's Avatar
    339 posts since Nov '06
    • i though is the glass filled with liquid more stable? sincer it is heavier,the cg will be lower?

  • FirePig's Avatar
    1,183 posts since Mar '08
    • Originally posted by 4794:

      i though is the glass filled with liquid more stable? sincer it is heavier,the cg will be lower?


      oh ya. Depends on what the glass is made of on the base and the sides.

  • Moderator
    eagle's Avatar
    17,973 posts since Aug '01
  • Moderator
    Darkness_hacker99's Avatar
    31,746 posts since Jun '05
    • Originally posted by 4794:

      i though is the glass filled with liquid more stable? sincer it is heavier,the cg will be lower?

      I'm thinking about this too

  • bonkysleuth's Avatar
    314 posts since Mar '07
    • Originally posted by eagle:

      TS, where did you see this question?


      O, that's extracted from my workbook. Eh, I find this question a little strange too. But I suppose it's got to do with the CG being a little higher. Yea, that's what i think.

  • Moderator
    eagle's Avatar
    17,973 posts since Aug '01
  • Moderator
    Darkness_hacker99's Avatar
    31,746 posts since Jun '05
    • It also depend on what external factor that cause the glass container to be unstable.


      Example: Using a detonator charge in an empty glass container.

      Of course the forces will be dissipate and there won't be a significant shocked wave produce.

       

       


      HOWEVER if the glass container is filled with water, things will be different.

      Quote: Wiki
      Initial damage to a target will be caused by the first shockwave; this damage will be amplified by the subsequent physical movement of water and by the repeated secondary shockwaves or bubble pulse.

  • weewee's Avatar
    498 posts since Aug '03
    • assuming glass is symmetrical, cg will be at the base of glass when empty. when water is added, cg will rise in height, making it easier to topple.

       

      however, when water is added, the weight is increased and more force will be needed to topple the glass.

  • Moderator
    eagle's Avatar
    17,973 posts since Aug '01
    • Originally posted by weewee:

      assuming glass is symmetrical, cg will be at the base of glass when empty. when water is added, cg will rise in height, making it easier to topple.


      however, when water is added, the weight is increased and more force will be needed to topple the glass.

      sentence in red is not true.

      the sentences in blue contradict each other.

  • weewee's Avatar
    498 posts since Aug '03
    • Originally posted by eagle:

      sentence in red is not true.

      the sentences in blue contradict each other.


      oh ya you are right.

      CG can be at a point which is not touching the glass....\*/

       When a bit of water is actually added, the CG will be lowered and thus stabilised the glass.

      When a lot of water is added in (water level mark way above original CG), the CG will be heightened and destabilised the glass.

      Edited by weewee 14 Apr `08, 2:17AM
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