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Turning effect of forces

  1. Apr 2, 2007 #1
    1. The problem statement, all variables and given/known data
    Discuss how a person's body is affected when lifting both light and heavy objects.

    2. Relevant equations
    No equations provided.

    3. The attempt at a solution
    The body's centre of gravity will be shifting at every moment. (I have a really poor grasp and understanding of physics concepts and this the only answer I can come up with. Please help me!)
  2. jcsd
  3. Apr 2, 2007 #2


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    Try drawing a stick figure lifting things, and try to arrow the forces.
  4. Apr 2, 2007 #3
    okay. How about something more graphic? The light and heavy part. For example, more on the centre of gravity part. Thanks for your help!
  5. Apr 7, 2007 #4
    Help! Thanks to everyone who answered, but I still do not understand!
  6. Apr 7, 2007 #5


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    Dearly Missed

    In order to actually lift a heavier weight, you'll need to provide a stronger force upon that object to counteract its own weight.

    Thus, at the very least, if you move it with constant velocity, it will, by Newton's 3.law, affect your arm with a force equal to its own weight.

    Thus, if you are not to fall through the ground, the ground must act upon you with a force equal to the sum of your own weight and the objects weight. That force is applied to your feet, presumably.
  7. Apr 7, 2007 #6
    Wow, that's quite the type of answers I had been looking for. Thanks!
  8. Apr 10, 2007 #7
    Hello thanks for the help I received since, but I really need more aid!
  9. Apr 16, 2007 #8
    hello please help me with this qn! Thanks!
  10. Apr 16, 2007 #9
    I'll toss in an experiment you can do at home. stand erect feet slightly apart, and lift one foot off the ground. assuming you have 2 legs, not too hard. Now with your right shoulder and arm pressed against a wall so that your hips, feet and shoulders are all perpendicular to the wall. Repeat above with left and right legs? What did you notice?
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