A phenomena i cant fully understnad

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    Phenomena
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Discussion Overview

The discussion revolves around the behavior of a rotating screw, particularly focusing on its motion at different speeds and the forces involved. Participants explore the mechanics behind the screw's tendency to stop and then rotate backwards after being spun at high speeds, considering various physical principles and analogies.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant suggests that the drag force acting on the screw has two components, which affect its behavior at low and high speeds.
  • Another participant proposes that the fast rotation might create a spring-like effect, where the screw behaves similarly to a compressed or extended spring.
  • A participant questions whether the observed behavior resembles that of a rattleback, providing a link for reference.
  • There is a suggestion that the length of the screw could influence its twisting behavior due to high torque, particularly when driven into hardwood.
  • One participant expresses skepticism about the rattleback analogy, proposing instead that the screw may roll on its thread when spun rapidly, leading to its backward rotation upon stopping.
  • Another participant encourages the original poster to create a video to better illustrate the phenomenon for further analysis.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the explanation for the screw's behavior, with multiple competing views and hypotheses presented throughout the discussion.

Contextual Notes

Some assumptions regarding the physical properties of the screw and the conditions of its rotation remain unaddressed, such as the specific environment in which the screw is rotated and the exact nature of the forces acting on it.

alexay95
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when i rotate a screw at low speed he stop after sec.
but when giving him high initial speed he rotate,stop,and rotate backwards and stop again.
i think its because the drag force which got 2 components,1 take care of low speed velocities and the other high speed.
i'm not fully understand that,and i hope someone can answer me.

*sry for my bad english,lol
 
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Where do you rotate the screw?
The fast rotation might lead to something like a compressed (or extended) spring, which reverses the direction to extend (or compress) again afterwards.
 
Is it a very long screw? Then driving long screws into hardwood I've seen the screw twist due to the high torque. Then when you stop the twist unwinds. It is most noticible on long screws that only have a thread at the pointed end like these...

http://www.screwfix.com/p/timberfix-plus-exterior-timber-screws-6-3-x-200mm-pk50/36687

Could also be a strobe lighting effect?
 
Last edited by a moderator:
0xDEADBEEF said:
Does it look like this? http://en.wikipedia.org/wiki/Rattleback

yes,but on an ordinery screw

http://0.tqn.com/d/homerenovations/1/0/A/A/-/-/1-5-8-Coarse-Drywall-Screw.jpg

about spring similarity,why would a hard screw act like 1?
 
If it is really just a screw I don't think the rattleback explanation works. What is probably happening, is that the screw can roll up on its thread at the tip a bit, when it is spun fast enough. When it comes to a rest it rolls back so the thread at the tip points up again. But if you don't think that is the reason, maybe you should make a video.
 

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