Vector Addition: Solving for Magnitude of B in C+B=7i+5j

AI Thread Summary
The discussion revolves around solving for the vector B in the equation C + B = 7i + 5j, where C is defined as 7i + 5j. The problem states that vector B, when added to C, results in a vector with a positive y-direction and a magnitude equal to that of C. Participants clarify that B must be expressed as -7i + yj, and they discuss how to find the value of y. The confusion lies in whether B or the resultant vector should match the magnitude of C, leading to different interpretations of the problem. Ultimately, the correct approach involves ensuring that the resultant vector's magnitude aligns with that of C.
jaciel2001cas
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I got a problem on a homework but the wording is kind of confusing and i don't know how to place it down on paper in a way that i can solve it...thanks for all the help..it looks basic, I find the Problem in weather its B+C=7i+5j or B+C=C being b+(7i+5j)=C

1: A vector, B, when added to the vector C=7i+5j yields a resultant vector which is in the positive y direction and has a magnitude equal to that of C. what is the magnitude of B?
 
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You know for sure that B = -7i + yj, how do you suppose you find what y should be? What is the magnitude of C? Do the two vectors look similar at all?
 
So magnitude of (B + C) = sqrt(7^2+5^2)
and the y component in A when added to C's y component has to be greater than 0.
 
im gettin 7.9 on the value of B..is that correct?
thanks for your help
 
Oh, which vector is supposed to have the same magnitude as C? If vector B is supposed to have the same magnitude then it should be B = -5i + (what)j, but if the resultant vector, call it D, is supposed to have the same magnitude then you need B = -5i + (you find it)j. Your answer would not be right for either case.
 
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