How do I integrate ax on the plane y=7?

[Melawrghk]

Homework Statement

The Attempt at a Solution

I get parts a and b, but I don't know what to do for part c.
I can write a double integral with dx and dz (because y is constant) and substitute y=7 in, but I'm not sure how to integrate a_x...

Any hints would be appreciated.

 

[diazona]

First, is a_x constant over the integration region? If so, you can pull it out of the integral, just as with a numeric constant.

If it's not constant, you'd need to find a way to express it in terms of things (i.e. other unit vectors) that are constant.

 

[Melawrghk]

Well I guess a_x is a unit vector in the x direction, so it must be constant.

But how do I figure out the limits of integration for x and z?

 

[diazona]

Well, what's the region of integration?

 

[Melawrghk]

I don't know, it just says plane y=7.