trying to decide if the following sentence is grammatical: What radius circle will a particle (mass m, charge q) follow if moving at speed v in a magnetic field B?

specifically the "what radius circle" bit

it seems grammatical to me, but i have no idea. and, there is sometimes a gap between grammatical and good exposition.

this is something ted could have answered, because when he went to school they still taught grammar

yeah, grammatical != "reads well"

(i'd hope that being grammatical is a necessary if not sufficient condition but i'm not confident of that)

part of the question is an implicit assertion, which is that a particle under those circumstances moves in a circle. if the point is that you don't want the student to prove/investigate/focus on that assertion, i might just state that fact - a particle doing bleh will move in a circle. now you, student, tell me the radius of that circle.

yeah, they're given the formula r=mv/qB on the equation sheet, and this is a multiple choice question

@Semiclassical it's not $\frac{mv^2}{qB}$?

in the last physics class i took, i think we did some kind of experiment relating to this equation to compute the mass of an electron.

no. mv^2/r = qvB, hence r=mv/qB

i'd say something about units but that would require me thinking about Tesla as a unit

ah, forgot that qvB was force

and life's too short for that

@robjohn ur mom is force!

Which branch does K-theory belong to, algebra or topology?

it began in algebraic geometry, in grothendieck's formulation of the riemann roch theorem, but topological K came pretty soon after

why not both

So it belongs to geometry then.

arxiv.org/abs/math/0012213

Too sadge geometry isn't broad enough to be considered the 4th branch.

Analysis, Algebra, and Topology are the three branches, but geometry?

@leslietownes you're pretty good at finding stuff on the internet. Are you a detective?

nope

@leslietownes do you have PhD??

where is all of this going. what do you really want to know?

@leslietownes your profession? But you're not telling me :(

i am a lawyer

i guess i forgot to answer that

@leslietownes so you have done math degree then you studied law?

yeah, why not

I think, you spend more time here than in court haha no offence :)

i don't know where you live or how the court system works there, but in the united states, it isn't exactly a badge of honor to have one's clients appearing in court all of the time

there's a good joke in the US about a country lawyer who says "i'm the greatest lawyer, every will i have written has been upheld by the supreme court"

the underlying premise of this joke is that you are f-ing up badly as an attorney if anything you do leads to a supreme court case

I can't find any wiki or nlab articles on tame sets and wild sets. Can someone suggest some references where I can find the definitions and basic stuffs about those?

i never saw such things, what field do they arise in?

3 manifolds. I don't know if they appear in other fields or not.