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B Do I weigh 50 kg or 50 * 9.8 kg?

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  1. Jul 22, 2016 #1
    When I take my weight, it often shows around 50 kg. However, in my Astronomy class currently, it was mentioned that an average person's mass is roughly around 50 kg.

    So, which one of them is correct? It doesn't make sense for my weight to be 50 kg because kg isn't exactly a unit of force, but then do I really weigh 490 N? (I'm so fat!)

    Thanks!
     
  2. jcsd
  3. Jul 22, 2016 #2

    CWatters

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    On earth your mass is 50kg and your weight (the force you exert on the ground) is 490 Newtons.

    On the moon your mass would still be 50kg but your weight would be 81 Newtons because gravity is lower.

    Most weighing scales (unsurprisingly) measure weight not mass but because they are intended for use on the earth only they are marked in Kg because that's what people are familiar with. They won't work correctly on the moon.
     
  4. Jul 22, 2016 #3

    fresh_42

    Staff: Mentor

    Just say you weigh .5 kN.
     
  5. Jul 22, 2016 #4

    CWatters

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    http://www.learnwithmac.com/2015/03/27/what-do-scales-measure/

     
  6. Jul 22, 2016 #5

    CWatters

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    I only weigh 21 Newtons*





    *(on Ceres)
     
  7. Jul 22, 2016 #6

    fresh_42

    Staff: Mentor

  8. Jul 22, 2016 #7
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