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Mass and size question

  1. Jul 22, 2012 #1
    does size matter when it comes to mass.For instance can something the size of a marble weight as much as a planet like earth?
  2. jcsd
  3. Jul 22, 2012 #2

    Simon Bridge

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    Size (re mass) matters when it comes to gravity at the surface or questions of density. The different forms of matter have the sorts of densities they do because there are repulsive forces balancing out gravity and whatever other pressures we can bring to bear.

    For something the mass of the Earth to get to be the size of a marble - there must be some mechanism to get it that small against the proton-proton repulsion as the nuclei squash together (for example). Thus, objects that dense tend to also be very large so the gravity can hold them together.

    Note: the Schwartzschild radius of an object of Earth mass is about 9mm ... a smallish marble would be about a centimeter across, so anything capable of shrinking an Earth mass to that scale is likely to create a black hole instead.
  4. Jul 23, 2012 #3


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    Are you aware of the concept of density?

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