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Homework Help: Physics Question for my kid

  1. Jan 21, 2013 #1
    My son has some science homework for a final this week.

    I am not a big physics guy. I studied sociology in college.

    Can you help us out with this question(s)?

    If you have a scale taped to your feet while standing on top of a building, and you jump off the building, what would your weight be on the scale while free falling? Before jumping, your weight was 120 lbs.

    Why are newtons like weight?
  2. jcsd
  3. Jan 21, 2013 #2


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    Weight is the product of both mass and gravity.
    Thus the reason why it's in Newtons.

    Acceleration of gravity is 9.81 m/s^2.

    Therefore.. your weight while free falling would be:

    W (Weight) = m (mass) X g (gravity)
    W = 0.12kg X 9.81 m/s^2
    W = 1.1772 N
  4. Jan 21, 2013 #3
    So you would actually weigh something while falling?

    I think these were two separate questions on his homework.
  5. Jan 21, 2013 #4
    The scale would read zero! All objects fall at the same rate!
    If you taped a scale to a mouse in free fall - the scale reads zero
    If you taped a scale to a elephant in free fall - the scale reads zero
    If you taped a scale to a _______ in free fall - it reads zero.
    You get my point
  6. Jan 21, 2013 #5
    No, his answer is incorrect. If things had different weights in free fall (relative), they would not fall at the same rate.
  7. Jan 21, 2013 #6


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    EDIT: Nevermind. My mistake. Read the question wrong, and didn't notice the word "scale". Haha
  8. Jan 21, 2013 #7

    No problem ;) I comment on here to quickly sometimes as well, then I regret my answer! haha
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