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Homework Help: What is wrong with this answer?

  1. Jul 4, 2010 #1
    Everything seems to make sense to me, but I know the answer is wrong..

    "Actually, mass and weight are not the same thing. Mass is how much of something there is - which does not change throughout the universe (mass = density * volume). Weight is a force, which is constantly changing throughout the universe depending on the acceleration of gravity (weight = mass * acceleration of gravity).

    You can work out a persons mass simple by dividing their weight by 9.806 (Earth's acceleration of gravity).

    For example, if your weight = 80 kilograms, then your mass would be 8.15 kilograms. Because -- 80 kilograms / 9.806 = 8.15 kilograms"
  2. jcsd
  3. Jul 4, 2010 #2
    You are absolutely right about all the descriptions. Why do you say you are wrong??

    The only errors I see is a possible rounding error, and a unit error.

    you said "weight = 80 kilograms" this is nonsensical. You yourself said weight is a force (and it is) so you would need "weight = 80 Newtons" or some other unit of force.
    Then when you divide by acceleration you would have "8.16 kilograms"
    Always put correct units on all numbers in calculations, you forgot units on your acceleration as well.

    It should look like:
    80 Newtons / 9.8 meters per second squared = 8.16 kilograms.
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