Transform vector to Cylindrical Coordinates

ph351
Messages
2
Reaction score
0
i need help transforming this equation into cylindrical coordinates...

w = omega
i = i hat
j = j hat
k = k hat
r is a vector

r(t) = Asin(wt)i + Bsin(wt)j + (Ct - D)k where w, A, B, C and D are constants.

i, j, and k are throwing me off...i know they are components of x, y and z...and i know xhat = cos(phi ro{hat}) - sin(phi phi{hat} likewise for yhat swapping sin and cos...
 
Last edited:
Physics news on Phys.org
ph351 said:
i need help transforming this equation into cylindrical coordinates...

w = omega
i = i hat
j = j hat
k = k hat
r is a vector

r(t) = Asin(wt)i + Bsin(wt)j + (Ct - D)k where w, A, B, C and D are constants.

i, j, and k are throwing me off...i know they are components of x, y and z...and i know xhat = cos(phi ro{hat}) - sin(phi phi{hat} likewise for yhat swapping sin and cos...

HI ph351, welcome to PF!:smile:

The \mathbf{\hat{i}}, \mathbf{\hat{j}}, and \mathbf{\hat{k}} are just another way of writing \mathbf{\hat{x}}, \mathbf{\hat{y}} and \mathbf{\hat{z}}. Different authors use different notations, and it is usually a good idea to familiarize yourself with the notation of a text before attempting to solve problems from it, or apply equation found in it. Other common notations for the Cartesian unit vectors are \{\mathbf{\hat{e}}_x,\mathbf{\hat{e}}_y,\mathbf{\hat{e}}_z\} and \{\mathbf{\hat{e}}_1,\mathbf{\hat{e}}_2,\mathbf{\hat{e}}_3\}.

So basically, you have \textbf{r}(t)=A\sin(\omega t)\mathbf{\hat{x}}+B\sin(\omega t)\mathbf{\hat{y}}+(Ct-D)\mathbf{\hat{z}}...and you can just make your substitutions for \mathbf{\hat{x}} and \mathbf{\hat{y}} in cylindrical coordinates.
 
Thread 'Need help understanding this figure on energy levels'
This figure is from "Introduction to Quantum Mechanics" by Griffiths (3rd edition). It is available to download. It is from page 142. I am hoping the usual people on this site will give me a hand understanding what is going on in the figure. After the equation (4.50) it says "It is customary to introduce the principal quantum number, ##n##, which simply orders the allowed energies, starting with 1 for the ground state. (see the figure)" I still don't understand the figure :( Here is...
Thread 'Understanding how to "tack on" the time wiggle factor'
The last problem I posted on QM made it into advanced homework help, that is why I am putting it here. I am sorry for any hassle imposed on the moderators by myself. Part (a) is quite easy. We get $$\sigma_1 = 2\lambda, \mathbf{v}_1 = \begin{pmatrix} 0 \\ 0 \\ 1 \end{pmatrix} \sigma_2 = \lambda, \mathbf{v}_2 = \begin{pmatrix} 1/\sqrt{2} \\ 1/\sqrt{2} \\ 0 \end{pmatrix} \sigma_3 = -\lambda, \mathbf{v}_3 = \begin{pmatrix} 1/\sqrt{2} \\ -1/\sqrt{2} \\ 0 \end{pmatrix} $$ There are two ways...
Back
Top