Is it possible to solve for “t?”

  • Context: Undergrad 
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Discussion Overview

The discussion centers around the possibility of solving for the variable "t" in a formula related to finding the quickest route between two horizontal points, specifically in the context of the brachistochrone problem. Participants explore the implications of known values for A and B on the ability to determine t, considering both algebraic and numerical methods.

Discussion Character

  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Some participants suggest that while A and B can be known, finding an exact solution for t algebraically may not be possible, with one mentioning the Lambert W function as a potential tool.
  • Others argue that numerical methods, such as Newton-Raphson, can yield approximate solutions for t, but note that multiple solutions may exist for given values of A and B.
  • One participant posits that the equation may have solutions in the complex domain, although they express skepticism about the practical application of such solutions.
  • There are discussions about the implications of rational and irrational values for A, B, and t, with some questioning the validity of certain statements regarding their relationships.
  • Participants express confusion about the relationship between the equations presented and the conditions under which solutions may or may not exist.

Areas of Agreement / Disagreement

Participants generally do not reach a consensus on whether t can be solved analytically when A and B are known. Multiple competing views remain regarding the methods of finding t and the nature of the solutions.

Contextual Notes

Limitations include the complexity of the equations involved, the dependence on definitions of rational and irrational numbers, and the unresolved nature of the mathematical steps required to find t from A and B.

  • #91
pbuk said:
I don't think you can. In any case the mathematical solution is useless, this is an engineering problem and yopu need to non-neglect all the neglected variables.

The resulting problem is only solvable (but trivially solvable) by computational methods.

There is nice approximate form of solution starting on bottom of 332 here:
https://www.jstor.org/stable/2974953?seq=5#metadata_info_tab_contents

Also, I think this is not an engineering problem, but quite a purely mathematical problem!
 
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  • #92
There's tons of open sourced info about this in Musk's hyperloop project, no need to pursue it further here.
 
  • #93
pbuk said:
There's tons of open sourced info about this in Musk's hyperloop project, no need to pursue it further here.
... where still the mathematical formula should be discussed, and not the physical system which led to it.

If someone wants to open a new thread about Hyperloop, please feel free to do so. Contact a mentor if you want some of the late posts here to be moved into the new thread in order to get it started.
This one will be closed.
 
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