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[Phys-L] Re: Area vector

Just a thought: area is an X * Y calc. Rt. hand rule would suggest the
Z direction for the area.

bc, who can't remember any text drwng. not observing this rule.

Joseph Bellina wrote:

Consider a region on the paper with an area. If you wanted to define a
direction, what criterion would you use to create a unique direction if
the vector were to lay in the plane of the page. Why is up the page
prefered to down the page, or to the left or right. Different people
with different prespectives, such as sitting on different sides of the
paper would chose different direction vectors. Conclusion, to avoid
confusion and be unique, the vector cannot have a component in the plane
of the paper. That leaves only a vector perpendicular to the page.



Kilmer, Skip wrote:

Parallel to the plane is ambiguous?

-----Original Message-----
From: Forum for Physics Educators []On
Behalf Of Tony Wayne
Sent: Tuesday, March 29, 2005 13:28
Subject: Area vector

Does any one know why the "area vector" for a surface is defined as
being normal to the plane of the surface instead of parallel to the
plane of the surface?
= = = = = = = = = = = = = = = = = = = = =
Tony Wayne

Joseph J. Bellina, Jr. Ph.D.
574-284-4662, 4968
Saint Mary's College
Dept. of Chemistry and Physics
Notre Dame, IN, 46556

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