Yes, this happens if and only if the two vectors are perperndicular:
Since the magnitudes are always positive we can WLOG equate their squares instead:
|a+b|^2 = (a+b)(a+b) = AA + 2ab + bb
|a-b|^2 = (a-b)(a-b) = AA - 2ab + bb
Which are equal iff ab = 0. So for instance take (1,0) and (0,1) as your two vectors and behold: |(1,1)| = |(1,-1)|.
When the vectors are parallel, i.e. both have the same direction.
Only if one of them has a magnitude of zero, so, effectively, no.
No two vectors of unequal magnitude cannot give the sum 0 because for 0 sum the 2 vectors must be equal and in opposite direction
Not really. The sum of the magnitudes is a scalar, not a vector - so they can't be equal. But the sum of the two vectors can have the same magnitude, if both vectors point in the same direction.
Yes. Vectors contain both magnitude and direction. Graphically three vectors of equal magnitude added together with a zero sum would be an equilateral triangle.
iff the angle between them is 120 degrees
180 degrees. Then the sum of the two vectors has a magnitude equal to the difference of their individual magnitudes.
The magnitude of the vector sum will only equal the magnitude of algebraic sum, when the vectors are pointing in the same direction.
When the vectors are parallel, i.e. both have the same direction.
Yes. A vector has magnitude and direction. If the vectors have equal magnitude and directly opposite directions their sum will be zero.
Only if one of them has a magnitude of zero, so, effectively, no.
No two vectors of unequal magnitude cannot give the sum 0 because for 0 sum the 2 vectors must be equal and in opposite direction
Not really. The sum of the magnitudes is a scalar, not a vector - so they can't be equal. But the sum of the two vectors can have the same magnitude, if both vectors point in the same direction.
Yes. Vectors contain both magnitude and direction. Graphically three vectors of equal magnitude added together with a zero sum would be an equilateral triangle.
When the angle between two vectors is zero ... i.e. the vectors are parallel ... their sum is a vector in thesame direction, and with magnitude equal to the sum of the magnitudes of the two original vectors.
Only if one of them has a magnitude of zero, so, effectively, no.
When all the vectors have the same direction.