Notices
Results 1 to 4 of 4

Thread: How do gravitational force lines work?

  1. #1 How do gravitational force lines work? 
    Administrator KALSTER's Avatar
    Join Date
    Sep 2007
    Location
    South Africa
    Posts
    8,231
    I was thinking. Let’s say you want to work out the gravitational attraction between two spheres. So you use the formula F = Gm1m2/r^2. That means you take it as if each body is attracted towards a point mass r distance away. But when you think about it, the resultant force coming from the mass at the horizons would have to be converted with Pythagoras to get the linear attraction in the direction of the centre of mass. Also, the other side of the body is farther away from you than the closer part. So how does that work? Does it all cancel out exactly as if Pythagorean conversions of the field lines were done from all points on each body? Maybe a stupid question :?


    Disclaimer: I do not declare myself to be an expert on ANY subject. If I state something as fact that is obviously wrong, please don't hesitate to correct me. I welcome such corrections in an attempt to be as truthful and accurate as possible.

    "Gullibility kills" - Carl Sagan
    "All people know the same truth. Our lives consist of how we chose to distort it." - Harry Block
    "It is the mark of an educated mind to be able to entertain a thought without accepting it." - Aristotle
    Reply With Quote  
     

  2.  
     

  3. #2  
    The Doctor Quantime's Avatar
    Join Date
    Jun 2007
    Location
    United Kingdom
    Posts
    4,546
    I suppose its like rolling down a hill, it doesn't matter which side you are on of the hill you will reach the middle at the same relativistic time :?.


    "If you wish to make an apple pie from scratch, you must first invent the universe". - Carl Sagan
    Reply With Quote  
     

  4. #3 Re: How do gravitational force lines work? 
    Forum Professor sunshinewarrior's Avatar
    Join Date
    Sep 2007
    Location
    London
    Posts
    1,525
    Quote Originally Posted by KALSTER
    I was thinking. Let’s say you want to work out the gravitational attraction between two spheres. So you use the formula F = Gm1m2/r^2. That means you take it as if each body is attracted towards a point mass r distance away. But when you think about it, the resultant force coming from the mass at the horizons would have to be converted with Pythagoras to get the linear attraction in the direction of the centre of mass. Also, the other side of the body is farther away from you than the closer part. So how does that work? Does it all cancel out exactly as if Pythagorean conversions of the field lines were done from all points on each body? Maybe a stupid question :?
    I can't do the maths myself, but that was one of Newton's triumphs. He demonstrated that, for a perfect sphere, the gravitational force acted exactly as though it were all concentrated at the single central point.

    By all accounts he invented the calculus in order to solve problems like this, although when he presented his findings (in his famous Principia) he derived his results using classical (Euclidean) geometry. I think the first step towards understanding it is the consideration of a solid sphere as a series of infinitesimally thin concentric shells. Try to imagine what the point (Centre of Gravity) for any given shell might be.
    Reply With Quote  
     

  5. #4  
    Forum Freshman Seraphimas's Avatar
    Join Date
    May 2012
    Posts
    12
    In a perfect sphere, wouldnt the center point stay the same no matter which concentric circle you use for measuring?
    The unexamined life is not worth living. - Socrates
    Reply With Quote  
     

Bookmarks
Bookmarks
Posting Permissions
  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •