Notices
Results 1 to 3 of 3

Thread: On the nature of motion....

  1. #1 On the nature of motion.... 
    Forum Sophomore
    Join Date
    Sep 2012
    Location
    Totnes in Devon, Mumbai and StAlban-Auriolles in Southern France
    Posts
    120
    I'm really not sure where to post this, perhaps physics? Maybe someone can guide me.

    I am aware of Zeno et al.

    Imagine a small fly, flying along a railway track directly towards an oncoming train with flat vertical forward facing surfaces.
    The fly hits the train at right angles to the flat surface...... The motion of the fly reverses direction. BUT without coming to a stop, for if it were to come to a stop then that would imply that the train came to a stop also, albeit for an instant. Clearly this is wrong, the train does not stop although it's velocity will have been reduced by an infinitesimal amount.

    This would seem to imply that a point can reverse direction of travel without becoming stationary.

    Or is this an issue of being stationary relative to some outside reference frame?

    Any useful comments appreciated....

    Chris


    Reply With Quote  
     

  2.  
     

  3. #2  
    Genius Duck Dywyddyr's Avatar
    Join Date
    Jan 2013
    Location
    Scunthorpe, UK
    Posts
    12,001
    The engineering explanation 1 is that "the train" isn't a monolithic prefectly rigid object (nor, for that matter, is the fly).
    A portion of the train will stop - that bit directly in contact (although when I first heard this conundrum ~40 years ago it was "ball bearing" rather than fly) and deform until the elasticity of the impact sends the fly/ bearing on its way. The material directly subject to the impact will absorb that impact, leaving a dent (even if of negligible/ undetectable depth).

    1 There's a mathematical one too, something about instantaneous halt, which, apparently, doesn't count as an actual halt...


    "[Dywyddyr] makes a grumpy bastard like me seem like a happy go lucky scamp" - PhDemon
    Reply With Quote  
     

  4. #3  
    Suspended
    Join Date
    Nov 2012
    Location
    Apocalyptic Paradise
    Posts
    6,613
    Quote Originally Posted by PhDemon View Post
    what's the last thing to go through a flys mind as it hits a windscreen? Its anus...
    Go boil your head.
    Reply With Quote  
     

Similar Threads

  1. Translating circular motion to linear motion
    By zollen in forum Mechanical, Structural and Chemical Engineering
    Replies: 3
    Last Post: May 31st, 2011, 01:55 AM
  2. Behavioral epigenetics - nature can effect our nature !
    By scishark in forum Behavior and Psychology
    Replies: 3
    Last Post: April 7th, 2011, 07:46 PM
  3. zero motion?
    By medlakeguy in forum Astronomy & Cosmology
    Replies: 33
    Last Post: March 20th, 2008, 11:23 AM
  4. Quantum mechanics and the nature of Nature
    By koantum in forum Philosophy
    Replies: 0
    Last Post: June 7th, 2006, 02:59 AM
  5. ABSOLUTE MOTION VS RELATIVE MOTION
    By MacM in forum Physics
    Replies: 115
    Last Post: August 9th, 2005, 07:12 PM
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
  •