Potential energy of a shoelace

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Discussion Overview

The discussion revolves around the potential energy stored in a tied shoelace, exploring various factors that may influence this energy, including material properties and the mechanics of knot tying and untying. The conversation includes experimental approaches to measure this energy and the complexities involved in such measurements.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant inquires about the potential energy stored in a tied shoelace.
  • Another participant raises questions regarding the material composition, tightness of the knot, and the modulus of elasticity of the substrate, suggesting these factors are crucial for understanding the potential energy.
  • A suggestion is made to measure the work done to undo the knot as a means to determine the potential energy, with a proposal to use a force-gauge for the experiment.
  • One participant argues that the work done to untie the knot is unrelated to the potential energy stored, citing the influence of friction and heat in the process.
  • Another participant questions the relationship between the work done in tying and untying the knot, referencing the concept of a "gordian knot" to illustrate that some knots may require significantly more work to untie than to tie.
  • A question is raised about whether energy stored as mass should be considered in this context.
  • One participant expresses confusion regarding the relevance of the previous question about mass energy.

Areas of Agreement / Disagreement

Participants express differing views on the relationship between the work done to untie a knot and the potential energy stored in the shoelace, indicating a lack of consensus on this issue. The discussion remains unresolved regarding the influence of various factors on potential energy.

Contextual Notes

The discussion highlights limitations in assumptions about the nature of forces involved in knot tying and untying, as well as the complexities introduced by friction and material properties. There is also ambiguity regarding the inclusion of mass energy in the potential energy consideration.

Rothiemurchus
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How much potential energy is stored in a tied shoelace?
 
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What's it made of? How tightly is it tied? What sort of substrate is it tied into, specifically with regard to modulus of elasticity in the area of the eglets? Getting the idea?
 
You can work this one out by measuring the work done it takes to undo the knot.

Anyone any ideas for doing this experiment? I suppose you could do it with a force-gauge.
 
christianjb said:
You can work this one out by measuring the work done it takes to undo the knot.
No. the two works are unrelated.
 
lpfr said:
No. the two works are unrelated.

How so?

I guess that it's nowhere near a conservative force field, so most of the work is done against friction, which ends up heating the shoe-lace.
 
christianjb said:
How so?

I guess that it's nowhere near a conservative force field, so most of the work is done against friction, which ends up heating the shoe-lace.

You have answered yourself.

Have you ever heard about a "gordian knot"? Some real life knots are almost gordian. They ask for very much work to untie than to tie.
 
are you including energy stored as mass?
 
I don't know whe you are asking. Anyway, not me!
 

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