Integrating a curve of position vectors

In summary, the conversation discusses different ways to express the derivative of a curve, specifically using circular and tangent/normal components. The concept of the Frenet Serret formula for a space curve is mentioned. The question of whether there is a way to express a vector integral in terms of information from the vector being integrated is also raised. The individual provides an example of using angle and magnitude values to create expressions for both the derivative and integral of a vector, but questions if it is possible to write expressions for integrals that depend on information from the vector being integrated.
  • #1
rabbed
243
3
I'm looking at different ways to express the derivative a curve, like circular and tangent/normal components.
Is there no such way that let's you express a vector integral in terms of information from the vector you want to integrate?
 
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  • #2
Can you provide some explicit examples for your curve and how you use circular and tangent/normal components?

My understanding is that you are referring to the Frenet Serret formula of a space curve is that right?

https://en.wikipedia.org/wiki/Frenet–Serret_formulas

Can you provide a context for the vector integral you're thinking about?
 
  • #3
No specific example at the moment, but I wanted some opinions if it would definitely be impossible or not.
Yeah, the Frenet Serret frame has come up in my searches, though I haven't investigated it yet.

I was able to create an expression for the derivative of a vector where I'm adding an angle value to the vector angle
and dividing a magnitude value with the vector length. Both values depend on x(t)*y'(t) - y(t)*x'(t) and x(t)*x'(t) + y(t)*y'(t).
Then I did the same for the integral of a vector, this time subtracting the same angle value and dividing the same magnitude
value by the length of the vector to be integrated. The values depended on the same quantities, but this time I had to integrate
the rectangular components: X(t)*y(t) - Y(t)*x(t) and X(t)*x(t) + Y(t)*y(t).

Expressions of derivatives depend on information of what is derivated, but is it impossible to write expressions of integrals depending on information of what is integrated (and without a sum/integral operator)?
I guess it boils down to that derivating is "lossy", so we can make chain, product rules for it, but not how to go the other way (in all cases)?
 
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  • #4
This is what I got:

derivative of (x(t), y(t)) = l(t)/sqrt(x(t)^2 + y(t)^2) * (cos( atan2(y(t),x(t))+a(t) ), sin( atan2(y(t),x(t))+a(t) ))
where
l(t) = sqrt( (x(t)*y'(t) - y(t)*x'(t))^2 + (x(t)*x'(t) + y(t)*y'(t))^2 )
a(t) = atan2( x(t)*y'(t) - y(t)*x'(t), x(t)*x'(t) + y(t)*y'(t) )

integral of (x(t), y(t)) = l(t)/sqrt(x(t)^2 + y(t)^2) * (cos( atan2(y(t),x(t))-a(t) ), sin( atan2(y(t),x(t))-a(t) ))
where
l(t) = sqrt( (X(t)*y(t) - Y(t)*x(t))^2 + (X(t)*x(t) + Y(t)*y(t))^2 )
a(t) = atan2( X(t)*y(t) - Y(t)*x(t), X(t)*x(t) + Y(t)*y(t) )
 
  • #5
@fresh_42 may have some ideas here as he's published some excellent insight articles on the various forms of derivatives.
 
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FAQ: Integrating a curve of position vectors

What is the purpose of integrating a curve of position vectors?

The purpose of integrating a curve of position vectors is to determine the total displacement of an object over a specific period of time. This can be useful in analyzing the motion of an object and determining its velocity and acceleration.

How is a curve of position vectors integrated?

A curve of position vectors is integrated by finding the area under the curve using calculus techniques. This involves breaking the curve into small segments and adding up the areas of each segment to find the total area.

What is the difference between integrating a curve of position vectors and integrating a velocity-time graph?

Integrating a curve of position vectors involves finding the displacement of an object, while integrating a velocity-time graph involves finding the change in velocity of an object. The former is a measure of distance, while the latter is a measure of speed.

Can integrating a curve of position vectors be used to determine the distance traveled by an object?

Yes, integrating a curve of position vectors can be used to determine the distance traveled by an object. The total area under the curve represents the total displacement of the object, which is equivalent to the distance traveled.

Are there any limitations to using integrals to analyze curves of position vectors?

One limitation of using integrals to analyze curves of position vectors is that it assumes the object is moving at a constant velocity. This may not always be the case in real-world scenarios, and more advanced mathematical techniques may be needed to accurately analyze the motion of an object.

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