# Manipulating derivatives and rearranging

• cooev769
In summary, the speaker is a third year physics student who is struggling to rearrange equations in their class in New Zealand. They are seeking help with rearranging the equations and also asking for advice on how to write equations on the forum. They later realize that the equations given were incorrect and the thread is closed.
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.

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.

jbunniii said:
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.

https://www.physicsforums.com/showpost.php?p=3977517&postcount=3

micromass said:
I linked it in my post too (see blue FAQ link) but now that I look at it, it doesn't show up very well.

jbunniii said:
I linked it in my post too (see blue FAQ link) but now that I look at it, it doesn't show up very well.

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

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

## What is the purpose of manipulating derivatives and rearranging?

The purpose of manipulating derivatives and rearranging is to simplify complex mathematical expressions and equations involving derivatives, making them easier to solve or understand.

## What are the most common techniques used for manipulating derivatives?

The most common techniques used for manipulating derivatives include the power rule, product rule, quotient rule, chain rule, and implicit differentiation.

## Why is it important to know how to manipulate derivatives?

Knowing how to manipulate derivatives is important for solving a wide range of mathematical problems in fields such as physics, engineering, and economics. It also helps in understanding the behavior of functions and their rates of change.

## Can manipulating derivatives help in finding the maximum or minimum points of a function?

Yes, manipulating derivatives can help in finding the maximum or minimum points of a function by setting the derivative equal to zero and solving for the critical points.

## How can we use rearranging to solve for a specific variable in an equation involving derivatives?

Rearranging involves isolating the desired variable on one side of the equation by performing inverse operations. By doing so, we can solve for the specific variable in terms of the other variables and constants in the equation.

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