Re: Barn-Pole Nuts & Bolts contradiction

Dear David:

"David" <dseppala@xxxxxxxxxxxxx> wrote in message
news:5p58d3d6aiubpjio3g828vkldtfp3j6ej7@xxxxxxxxxx
This problem is the classic Barn Pole paradox with
the barn replaced by a long threaded nut and the
pole replaced by a long threaded rod.

Let there be a threaded nut of length L and a
threaded rod also of length L as measured in a
rest frame. Let each of these have N threads.
Now let the threaded rod and threaded nut move
toward each other with equal and opposite
velocities as measured in this rest frame. And
let the threaded nut and the threaded rod each
rotate such that when they meet the rotation
rate is such that threaded nut and threaded rod
fit perfectly and neither the rod nor the nut
undergo any acceleration.

How do you have rotation without acceleration, David?

How is this viewed using SR in the rest frame
of the nut?

Note that for any appreciable axial velocity, the tangential
velocity will be many times greater... depending on the pitch.

In this frame, per SR, the threaded
rod spans a shorter distance than the threaded
nut.

No, because the surface of the threaded rod is moving at an angle
to the nut's central axis. You are ignoring the meshing surface,
while concentrating on the "center of mass".

So that when the rod is completely
encased by the nut,as viewed in the inertial
frame of the nut, the N threads of the rod span
less than the N threads of the nut. I don't see
how this is physically possible. Can someone
explain this using SR concepts.

SR doesn't do acceleration simply enough that you can understand,
David. It seems to keep leaking out of your head.

David A. Smith


.

Relevant Pages

  • Barn-Pole Nuts & Bolts contradiction
    ... This problem is the classic Barn Pole paradox with the barn replaced ... by a long threaded nut and the pole replaced by a long threaded rod. ... length L as measured in a rest frame. ...
    (sci.physics.relativity)
  • Re: Barn-Pole Nuts & Bolts contradiction
    ... pole replaced by a long threaded rod. ... Now let the threaded rod and threaded nut move ... velocities as measured in this rest frame. ... known I meant linear acceleration. ...
    (sci.physics.relativity)
  • Re: Barn-Pole Nuts & Bolts contradiction
    ... by a long threaded nut and the pole replaced by a long threaded rod. ... How is this viewed using SR in the rest frame of the nut? ... You repeatedly and consistently ignore what people keep telling you, and making the same mistakes. ...
    (sci.physics.relativity)