Determining double integral limits

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The discussion focuses on evaluating the surface integral of a vector field over a portion of a circular cylinder defined by the equation x² + y² = 16, projected onto the xz-plane. Participants express confusion regarding the integration limits, particularly due to the lack of specified height for the cylinder in the z-direction. It is noted that the projection on the xz-plane must be visualized to determine the correct limits for integration. The limits provided in the solution are questioned, as the absence of height makes the problem seem ill-defined. Clarification on the problem statement and the definition of region R is sought to resolve these issues.
JasonHathaway
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Homework Statement



Evaluate \iint\limits_S \vec{A} . \vec{n} ds over the plane x^{2}+y^{2}=16, where \vec{A}=z\vec{i}+x\vec{j}-3y^{2}\vec{k} and S is a part from the plane and R was projected over xz-plane.

Homework Equations



Surface Integral and Double Integration.

The Attempt at a Solution



This is an answered problem, but I didn't get how to determine the integration limits

I understand that I have to integrate with respect to x and z due the fact the region is projected over "xz-plane", and I've to get the limits from the plane equation.

The limits integration in the solution are \int_0^5 \int_0^4 dz dx
 
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JasonHathaway said:

Homework Statement



Evaluate \iint\limits_S \vec{A} . \vec{n} ds over the plane x^{2}+y^{2}=16, where \vec{A}=z\vec{i}+x\vec{j}-3y^{2}\vec{k} and S is a part from the plane and R was projected over xz-plane.

Homework Equations



Surface Integral and Double Integration.


The Attempt at a Solution



This is an answered problem, but I didn't get how to determine the integration limits

I understand that I have to integrate with respect to x and z due the fact the region is projected over "xz-plane", and I've to get the limits from the plane equation.

The limits integration in the solution are \int_0^5 \int_0^4 dz dx

##x^2+y^2=16## is not a plane. It's a circular cylinder standing on the xy plane. And you haven't told us how high it goes in the z direction. Draw a picture to see what its projection on the xz plane would look like.
 
And that's what confusing me, there's no height. So the problem is wrong, isn't?
 
I can't make sense of the problem statement. What is R? Is this quoted word for word?
 
Question: A clock's minute hand has length 4 and its hour hand has length 3. What is the distance between the tips at the moment when it is increasing most rapidly?(Putnam Exam Question) Answer: Making assumption that both the hands moves at constant angular velocities, the answer is ## \sqrt{7} .## But don't you think this assumption is somewhat doubtful and wrong?

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