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Homework Help: G-Force and (possibly) Centrifugal force applied to the rotation of a car

  1. Jun 3, 2012 #1
    1. I'm in my first year of physics, and the end-of-year project is a bit of a doozy: find two examples of misapplied physics in movies and explain how it's wrong. For my first example, I chose a scene from the movie "The Iron Giant," in which the Giant picks up a car with Hogarth, our child protagonist, inside, and then rotates his torso incredibly fast, like a merry-go-round. I noticed that despite the incredible speed, no "centrifugal" force was being applied; Hogarth was sitting in the driver's seat, but not moving towards the outside of the car.
    I'm having trouble with the centrifugal force, which I believe is an equal-but-opposite reaction to centripetal force (though I'm not quite sure), and calculating the G-force, which I'm not sure how to do.

    radius- assuming Hogarth's claim that the Giant is 100 ft. tall, and that the Giant is similarly proportional to a human, the radius - the length of his arm- would be approximately 50 feet, or 15.24 meters.
    Speed- about 5 revolutions in 2 seconds- 150 revolutions in 1 minute, or 1 revolution in 0.4 seconds.
    Velocity- 239.39 meters/second.
    Mass- assuming the mass of the car is about 5000 lbs. and Hogarth is about 80 lbs., then their combined total is about 2304.25 kg.
    Centripetal acceleration- 3,755.94 meters per second squared
    Centripetal force- 8,654,630 N

    2. Ac = V squared / r
    V = (2∏r)/T
    Fc = (m[V squared]) / r

    3. I've found a bunch of factors, but I'm not sure how they relate to each other and how they show that Hogarth should be suffering from more G-force and moving outwards.
    And I'm not sure I'm even applying the correct equations or principles, or if what I'm trying to find is what I actually need to find.
    Last edited: Jun 3, 2012
  2. jcsd
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