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December 2009

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Subject:
From:
Lee parker <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Lee parker <[log in to unmask]>
Date:
Wed, 16 Dec 2009 16:38:16 -0500
Content-Type:
text/plain
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text/plain (113 lines)
To the contrary Ahne, when any object is rotating it is experiencing an acceleration. An acceleration is any change in the velocity vector, i.e. magnitude or direction. The magnitude of the acceleration, assuming the magnitude of the angular velocity is constant, is the radius from the center of rotation to the object multiplied by the square of the angular velocity.
Best regards.

Lee
J. L. Parker Ph. D.
JLP Consultants LLC
804 779 3389
    
  ----- Original Message ----- 
  From: Ahne Oosterhof<mailto:[log in to unmask]> 
  To: [log in to unmask]<mailto:[log in to unmask]> 
  Sent: Wednesday, December 16, 2009 3:49 PM
  Subject: Re: [TN] Tensile strrength


  A component on a board that is rotating at "big number" RPM is not being
  subjected to acceleration (except during the run-up time). But while it is
  rotating and sitting on the edge of the board it experiences quite a bit
  centrifugal force. Once it flies away it actually only sees a little
  deceleration (unless it gets blocked in its path by Inge's safety shield).

  Having fun,
  Ahne.

  PS: If this board is rotating at that high speed in air, it may experience
  some flexing also. (One more problem to add to the investigation.)
  This problem must be an mechanical engineer's dream (or nightmare).


  -----Original Message-----
  From: TechNet [mailto:[log in to unmask]] On Behalf Of Louis Hart
  Sent: Wednesday, 16 December, 2009 11:42
  To: [log in to unmask]<mailto:[log in to unmask]>
  Subject: Re: [TN] Tensile strrength

  Ahne, Technetters, keep in mind Newton's second law. If something is being
  accelerated, it is experiencing a force. If it is not being accelerated,
  there is no net force.

  A force is required to keep an object moving in a circle, or ellipse (as the
  Earth in its orbit), since the object's velocity is changing and it is
  accelerating, constantly. After the part is ripped off, the only force it
  experiences is that of gravity so it will be accelerated toward the center
  of mass of the Earth.

  A while back I read something by some philosopher, something like 'Newton's
  theory of motion is the greatest intellectual achievement in human history'.

  Einstein's General Theory of Relativity connecting gravitational mass with
  the mass in Newton's second law must be way up on the list of intellectual
  achievements, but I haven't gotten a good grasp of it. Any Technetters who
  can help me understand it, please let me know offline.

  Louis Hart

  -----Original Message-----
  From: TechNet [mailto:[log in to unmask]] On Behalf Of Ahne Oosterhof
  Sent: Wednesday, December 16, 2009 12:37 PM
  To: [log in to unmask]<mailto:[log in to unmask]>
  Subject: Re: [TN] Tensile strrength

  And I expected to see "force", not "acceleration".
  (The acceleration comes after the force has ripped the part off the board.)


  Having fun,
  Ahne

  -----Original Message-----
  From: TechNet [mailto:[log in to unmask]] On Behalf Of Thayer, Wayne - IIW
  Sent: Tuesday, 15 December, 2009 17:10
  To: [log in to unmask]<mailto:[log in to unmask]>
  Subject: Re: [TN] Tensile strrength

  Just to add a number to this, I get over 9000G's of acceleration on the
  parts near the ends of this board!

  Wayne Thayer

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