Recent content by deananderson

My question is for you. The task is to derive ##d\textbf{r}## by differentiating ##\vec{r}## and you used the result ("it is always ##d\textbf{r} = d\rho\hat{\rho} + \rho d\phi\hat{\phi} + dz\hat{z}##. When I do this, I also get four terms. The extra term is ##-\phi\hat{\rho} d\phi## I...

You can't just declare the answer! You have to derive the result using the same process as in any coordinate system: \begin{align} d\bold{r} =& d (r\hat{r}) = r\left(\frac{\partial r}{\partial \rho}d\rho + \frac{\partial r}{\partial \phi}d\phi + \frac{\partial r}{\partial z}dz\right) \\...