If u is a constant vector then curl u= 0. But then you say "where dS= u" which makes no sense- dS isn't constant except on planes.
Hi guys! I hope someone here will be able to help me with this question:
f(r) is a scalar field, then use stoke's theorem (∫∫c curlF.dS=∫cF.dr) to deduce that:
∫∫s grad(f) x dS = -∫c f dr
I am stuck as to how to do this. I have tried subbing in the vector calculus identity curl(fu)=fcurl(u)+(gradf)xu (where u is a constant). Thus
∫∫s grad(f) x dS = ∫∫s curl(fu) - fcurl(u) (where dS is u)
but I am not sure whether this is right (and i then get stuck at this point too). Please help!
Sorry, I don't quite understand. This question got moved from differential equations because I placed it there by accident, but I began only one thread for this question.
Sorry again. I didn't realise someone else had started a thread about this question. Do I have to ask a question on that thread now?