Solving Vector A: What am I Doing Wrong?

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Homework Help Overview

The discussion revolves around determining the angle of a vector with respect to the X-axis, specifically addressing the interpretation of angle measurements in different orientations. The original poster expresses confusion regarding the expected answer and the implications of negative angles in their calculations.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the validity of the calculated angle of -71.1 degrees and whether the correct interpretation involves converting it to a positive angle by adding 360 degrees. There is also a concern about the automated grading system's handling of negative angles.

Discussion Status

The conversation is ongoing, with participants exploring different interpretations of the angle measurement and the implications of the grading system's requirements. Some guidance has been offered regarding the potential limitations of the automated system, but no consensus has been reached on the correct approach.

Contextual Notes

Participants mention the instructions specifying that the angle should be measured counterclockwise from the +x axis, raising questions about the grading criteria and the expected format for submitting answers.

QuarkCharmer
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Homework Statement


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Homework Equations



The Attempt at a Solution



So, given these two components of the vector A, to find the angle the vector makes with the X axis I simply did the following:

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So theta is -71.1 with significant figures.

and that's not the expected answer either?
What am I doing wrong?

Do they really want the angle "measured counterclockwise from that axis" meaning:
360-71.1 ?
 
Last edited:
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Do they really want the angle "measured counterclockwise from that axis" meaning:
360-71.1

-71.1 looks right, so does 360-71.1. You have 4 shots left, why not give it a try?
 
lewando said:
-71.1 looks right, so does 360-71.1. You have 4 shots left, why not give it a try?

I think each "shot" takes off some points. Because the instructions says that it wants the angle counterclockwise from the +x axis, (which I assume is the positive side of the x axis) then I am thinking that the latter answer is correct.

This is silly, considering all the talk about "bowtie" angles and whatnot by my actual professor in class.
 
If the automated answer checking machine cannot deal with negative angles, that is a limitation of the machine, not you. If, as a result of this machine limitation, you have wasted a shot by entering a perfectly valid -71.1 degrees (with respect to positive angles being measured in the CCW direction from the +x axis) then you should insist that your professor return those couple of points only if you are between grades and think that a couple of points will matter. Otherwise, don't worry about it and fire away with the positive angle answer.

P.S. How do you know the machine is looking for degrees, not radians? What are the ground rules for submitting angle results?
 
lewando said:
P.S. How do you know the machine is looking for degrees, not radians? What are the ground rules for submitting angle results?

There is a little degree symbol next to the answer field.

I'm down to my last shot at this question, this is frustrating because I know that every single one of my answers were correct.
 

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