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

[PLAIN]http://img231.imageshack.us/img231/636/question2m.jpg [Broken]

2. Relevant equations

v = [tex]\dot{r}[/tex] [tex]\hat{r}[/tex] + r[tex]\dot{\vartheta}[/tex] [tex]\hat{\vartheta}[/tex]

3. The attempt at a solution

[tex]\dot{r}[/tex] = ?

\vartheta = 80°

v = 55mm/s

So I guess I just use the formula above.

v = [tex]\dot{r}[/tex] [tex]\hat{r}[/tex] + r[tex]\dot{\vartheta}[/tex] [tex]\hat{\vartheta}[/tex]

55² = [tex]\dot{r}[/tex]² + rΘ'

And so you try and solve for [tex]\dot{r}[/tex]

r'² = 55² - (r*Θ')²

r' = sqrt(55² - (r*Θ')²)

And then I get stuck. I am either missing something. Or not doing something right. I guess this isn't really r theta, it is more a conversion from r theta to x-y.

Not 100% sure how to do that though.

Cheers

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# Homework Help: Constrained to move Horizontally

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