(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

calculate the frenet frame for the vector:

[itex]\vec{r}(t)=(2t cost,2tsint,5t)[/itex]

calculate the acceleration in frenet frame.

2. Relevant equations

[itex]\hat{T}=\frac{dr}{ds}=\frac{\dot{r}}{|\dot{r}|}[/itex]

[itex]\hat{N}=\frac{\frac{dT}{ds}}{|\frac{dT}{ds}|}[/itex]

[itex]\hat{B}=\hat{T}\times \hat{N}[/itex]

3. The attempt at a solution

I'm not too sure how to get to [itex]\vec{r}(s)[/itex]

what I tried is : [itex]s=2t \ \ \Rightarrow \vec{r}(s)= s(\cos \frac{s}{2},\sin \frac{s}{2},2.5)[/itex]

[itex]T=\frac{dr}{ds}=s(-\sin \frac{s}{2},\cos \frac{s}{2},0)+(\cos \frac{s}{2},\sin \frac{s}{2},2.5)[/itex]

which is NOT a unit vector.

if I try use t as the variable it's just becomes a gigantic answer.

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# Homework Help: Frenet frame

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