Orthogonality of time dependent vector derivatives of constant magnitude

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Discussion Overview

The discussion revolves around the orthogonality of the derivative of a time-dependent vector function that maintains a constant magnitude. Participants explore the implications of this property and seek clarification on the underlying reasoning.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification

Main Points Raised

  • One participant expresses confusion regarding why the derivative of a time-dependent vector function is orthogonal to the original function.
  • Another participant asks for clarification on the specifics of the question, indicating a need for more detail.
  • A question is raised about whether the time-dependent vector indeed has a constant magnitude.
  • It is confirmed that the vector function is of constant magnitude, and a participant asserts that the derivative should be orthogonal to the original vector function.
  • A suggestion is made to differentiate the equation relating the vector's magnitude squared to explore the relationship further.

Areas of Agreement / Disagreement

Participants do not seem to reach a consensus on the reasoning behind the orthogonality, and the discussion remains unresolved with varying levels of understanding and clarification sought.

Contextual Notes

The discussion lacks specific mathematical steps or definitions that could clarify the reasoning behind the orthogonality claim, and assumptions about the vector's properties are not fully explored.

lordkelvin
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I'm having trouble understanding why a derivative of a time dependent vector function is orthogonal to the original function. Can anybody give me some enlightenment? I searched around for some previous talk about this, and I can't find anything.

Thanks.
 
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You have to be a bit more specific... I don't understand your question right now.
 
Does the time-dependent vector have constant magnitude?
 
Yes the original vector function is of constant magnitude. Take a vector function r(t) of constant magnitude and then r dot should be orthogonal to r. I don't understand why.
 
Take the derivative with respect to time of both sides of

r^2 = \bold{r}\left( t \right) \cdot \bold{r}\left( t \right).

What do you get?
 

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