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Finding Mass of Object without Scale

  1. Jul 20, 2005 #1
    I need to find the mass of an aluminum rod without the use of a scale. I have all the dimensions of the rod but I just don't know the right equations etc. Thanks for the help!
  2. jcsd
  3. Jul 20, 2005 #2


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    This sounds like it might be a homework problem. Perhaps you know the volume of the rod, and its density?

    Maybe you're stuck finding the volume of a "rod". A "rod" could have a lot of shapes, though the first one that springs to mind is that of a circular cylinder.

    I think that if this is a homework problem you'd do better if you made some effort to solve it yourself, first (the "show your work" rule) - also, there is a special forum for homework problems.
  4. Jul 20, 2005 #3
    You can accelerate it with a constant force and then divide the force exerted and the acceleration and that will give you the mass. Easy to say, hard to do for a lab experiment in school.

  5. Jul 20, 2005 #4


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    Yes, but how are you going to calculate the force with which you accelerate? you may still need a scale.
  6. Jul 20, 2005 #5
    It depends on the particular way you choose to accelerate it. If you use two charges then you use Coulombs law. If you use a spring then you use the law for springs (the name evades me at the moment).

  7. Jul 21, 2005 #6
    Would this be Hooke's Law ([itex]F = kx[/itex])? Sorry if I'm wrong, I just like to think I know what's going on once in a while :tongue:
    Last edited: Jul 21, 2005
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