Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Physics Brainteasers

  1. Dec 1, 2009 #1
    What weighs more, a frying pan in a dark room, or one that is outside on a sunny day?

    Which has more mass, a frying pan in a dark room, or one that is outside on a sunny day?

    Which weighs more, a frying pan at ground level or one 500 meters above the ground?

    Which has more mass, a frying pan at ground level, or one 500 meters above the ground?
  2. jcsd
  3. Dec 1, 2009 #2
    Maybe this should be in the physics section. Idk how to move posts though, or rename them...
  4. Dec 2, 2009 #3
    they all weigh the same and have same mass.
  5. Dec 3, 2009 #4


    User Avatar
    Science Advisor
    Gold Member

    Assuming they are the same frying pan, they will always have the same mass.

    A frying pan 500m above the Earth will weight slightly less than a frying pan located ON Earth due to the increased distance and therefore slightly lower gravity.

    A frying pan (the pan itself) weighs the same in both a dark and closed room; however, if you consider the effects of dust/pollen this may change depending on how dusty your room is! Also, the light from the sun will very very very gently push down on the frying pan, making weight measurements of it very slightly higher, but the frying pan itself doesn't weigh more.
  6. Dec 3, 2009 #5

    So, the one outside will have absorbed solar energy. But, since mass and energy are directly related (E=mc2), the mass increases as well--although by a tiny amount.
  7. Dec 17, 2009 #6
    Sunny day. E=mc2 and energy is mass, so the hotter pan would have more mass. More mass means greater mutual gravitational attraction, therefore, more weight.

    This question should have preceeded the first. The hot pan has more mass, and mass weighs more. So the sunny day.

    Ground level, as it's closer to the primary mass (Earth).

    No difference (and there's no gravitational mass dilation as there is with time. That I know of...)

    On second thought... We know time slows down and mass increases with relative velocity, so if gravitational time dilation holds, would gravitional mass increase hold as well? I'm thinking this may be the difference in Schwarzschild radii we see between rotating and non-rotating BH's, as per http://en.wikipedia.org/wiki/File:Mass_Properties.PNG" [Broken].

    Ok, I'll go out on a limb - the frying pan at ground level has more mass.

    Hey, I'm no brainsnot, so if you have different answers and rational justifications, I'm all ears!
    Last edited by a moderator: May 4, 2017
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook