Re: Transverse versus parallel torques -- did I miss something here?

From: J.J. Simplicio (abc_at_nospam.com)
Date: 07/23/04 

Date: Fri, 23 Jul 2004 14:02:23 GMT

"Bilge" <dubious@radioactivex.lebesque-al.net> wrote in message
news:slrncg1i7p.cg0.dubious@radioactivex.lebesque-al.net...
> J.J. Simplicio:
>
> >We can assume that in the frame of the lever, four forces just happen
> >to be applied simultaneously such that the lever remains in equilibrium
>
> You need o stop and re-examine exactly what you are assuming.
>
> >I don't follow what you're saying here. If a force is suddenly applied,
> >then the torque due to that force is also suddenly applied at that same
> >instant - i.e., the force and torque are simultaneous.
>
> In other words, you have no objection to the force propagating
> faster than light to the pivot point?
>

Suppose we have four people in the rest frame of the lever- Ed, Ted, Jed,
and Fred. Each person is responsible for applying one force to the lever.
Ed is to apply a 1 lb force in the negative x-direction at the upper tip of
the vertical leg of the L-shaped lever. Ted is to apply a 1 lb force in the
negative y-direction at the right tip of the horizontal leg. Jed will apply
a 1 lb force in the positive x-direction at the pivot and Fred will apply a
1 lb force in the positive y-direction at the pivot. Each person is
stationed at his/her respective point. They all agree to apply their forces
when their synchronized watches read 12 o'clock.

Seems to me this would make the application of all four forces simultaneous
in this frame. Each force is applied independently. None of the four
forces is the cause of any of the other four forces. Are you concerned
about the fact that immediately after the forces are applied there will be
stresses that spread throughout the lever at less than the speed of light
until equilibrium is achieved throughout the lever?

JJ

Relevant Pages

  • Re: RSX Front shifter
    ... > frame tubes. ... Shimano RSX seems to throw ... and the shifter is combined with the ... If wanting a new combined brake/gear lever for the left brake lever & front ...
    (uk.rec.cycling)
  • Re: "The Right Angle Lever Paradox"
    ... >the moving frame, both of these forces on each lever would undergo the ... the total force is zero in the rest frame, ... There is no rotation about the pivot, so the torques at the pivot must ...
    (sci.physics.relativity)
  • Re: Transverse versus parallel torques -- did I miss something here?
    ... > which the lever is moving, there is a vertical 'flow' of mass/energy ... > even though he doesn't explicitly mention this flow when discussing the ... but you always do it in the frame of reference associated ... > I always presume that when calculating the angular momentum in some ...
    (sci.physics.relativity)
  • Re: Transverse versus parallel torques -- did I miss something here?
    ... > where I is the momentum tensor and w is the rotational velocity, ... I suspect that you have to consider the stresses that exist in the lever. ... believe these stresses imply that in the reference frame in which the lever ... then mass/energy enters the end of the vertical leg, ...
    (sci.physics.relativity)
  • Re: SIS 6603 (Ultegra Triple) short reach conversion?
    ... I'll also point out that you can get all the brake power ... cable required that the the lever pivot move. ... pivot changes the ergonomics of braking from the hoods. ...
    (rec.bicycles.tech)