Anyone take a look at this vector calculus question for me:(adsbygoogle = window.adsbygoogle || []).push({});

=====

Q. Ifnis the uni normal to the surface S, evaluate Double Integralr.ndS over the surface of a sphere of radius 'a' centred at the origin.

=====

So I did:

r= (x,y,z)

Sphere: x^2 + y^2 + z^2 = a^2

let f = x^2 + y^2 + z^2

n=gradf / |gradf|

thereforen= (x,y,z)/a

n.r= a

Now how do I proceed with the integral? I thought it would just be

int(2pi->0) int (pi->0) int(a->0) a r.dr.d[theta].d[phi]

which gives the answer [pi]^2.[a]^3 which really doesn't look right! I think it's the actual integral I've made a mistake with! HELP!!!! I HATE VECTOR CALCULUS [and I really need to learn to use latex!]

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Vector Calculus Question

**Physics Forums | Science Articles, Homework Help, Discussion**