Manipulating derivatives and rearranging

1. Mar 24, 2014

cooev769

Hey, I am actually a third year physics student, but here in New Zealand they tend to rush past the fundamentals, hence I can't seem to rearrange the following equations properly. Eq 1 and Eq 2 are:

τ=-erB*dr/dt ek

and

τ=m*d(r^2dθ/dt)/dt ek

Where ek is a unit vector. Is supposed to be rearranged to the form:

vθ(r) = (-eB/mr) * integral between r and a of r dr = (-eB/mr)*(r^2-a^2)/2

I can get very close but my derivative rearranging is sub-optimum. A little help would be really appreciated, as would telling me how the hell I write equations on the forum. Cheers.

2. Mar 24, 2014

jbunniii

Regarding how to typeset equations on PF, there's a nice tutorial in section 2 of the FAQ, which should be more prominently visible but can be found under the "Site Info" link at the top of the page.

3. Mar 24, 2014

micromass

Staff Emeritus
4. Mar 24, 2014

jbunniii

5. Mar 24, 2014

micromass

Staff Emeritus
I totally missed that... Perhaps I'm going blind

6. Mar 24, 2014

cooev769

Cheers. Turns out the equations they gave us to derive was incorrect. So thread closed.