Vector Mag: When Does u+w > mag(u)+mag(w)?

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SUMMARY

The discussion centers on the mathematical condition under which the magnitude of the sum of two vectors, mag(u+w), exceeds the sum of their magnitudes, mag(u) + mag(w). This occurs when vectors u and w are not aligned in the same direction, specifically when they form an angle less than 180 degrees. The triangle inequality theorem is crucial here, as it establishes that the length of the third side (u+w) can be greater than the sum of the other two sides (u and w) only in specific geometric configurations. The discussion emphasizes the need to consider cases where vectors are parallel or antiparallel to fully understand the conditions.

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Homework Statement


If a vector "u" is added to a vector "w", under what circumstances will the value of mag(u+w) ever be greater than mag(u)+mag(w)?

Homework Equations


Magnitude = Sqrt( (Sum of x components)^2 + (sum of y components)^2 )

The Attempt at a Solution



I really, have no idea where to begin... I guess I could set up an equation and try to solve for the variables... Could someone point me in the right direction?

Thanks for all the help!
 
Last edited:
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Think of your two vectors as representing two sides of a triangle, and their sum as the third side of the triangle. What is the longest possible length that that third side in terms of the lengths of sides u and w?

Note: You either have to extend the concept of triangle here a bit to accommodate the cases where u and v are parallel or antiparallel, or you can cover those as special cases.
 

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