- #1
Lancelot59
- 646
- 1
I'm not sure why, but I'm having issues with these in general. Specifically surface integrals over vector fields.
The function is zk. The surface is the paraboloid z=x2+y2 between the planes z=1 and z=2.
I parametrized it like so:
[tex]\vec{r}(u,v)=(u,v,u^{2}+v^{2})[/tex]
[tex]\vec{T_{u}}=(1,0,2u)[/tex]
[tex]\vec{T_{v}}=(0,1,2v)[/tex]
[tex]\vec{N}=(-2u,-2v,1)[/tex]
putting r into F:
[tex]\vec{F}(\vec{r}(u,v))=(u,v,u^{2}+v^{2})[/tex]
The integral then wound up being
[tex]\int_{D}\int \vec{F(\vec{r})} \cdot \vec{N} = \int_{D}\int u^{2}+v^{2} dv du = \int^{2}_{0} \int^{2\pi}_{0} r^{2} * r dr d\theta = 16\pi[/tex]
Which is apparently wrong. What's going on here?
The function is zk. The surface is the paraboloid z=x2+y2 between the planes z=1 and z=2.
I parametrized it like so:
[tex]\vec{r}(u,v)=(u,v,u^{2}+v^{2})[/tex]
[tex]\vec{T_{u}}=(1,0,2u)[/tex]
[tex]\vec{T_{v}}=(0,1,2v)[/tex]
[tex]\vec{N}=(-2u,-2v,1)[/tex]
putting r into F:
[tex]\vec{F}(\vec{r}(u,v))=(u,v,u^{2}+v^{2})[/tex]
The integral then wound up being
[tex]\int_{D}\int \vec{F(\vec{r})} \cdot \vec{N} = \int_{D}\int u^{2}+v^{2} dv du = \int^{2}_{0} \int^{2\pi}_{0} r^{2} * r dr d\theta = 16\pi[/tex]
Which is apparently wrong. What's going on here?