draotic
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Homework Statement
Vector 'A' is along postive z-axis and its vector product with another vector 'B' is zero , then vector 'B' could be ..
a) i + j
b) 4i
c) i + k
d) -7k
.
wbandersonjr said:What do you think? What have you tried, or what equations are useful?
tiny-tim said:hi draotic!
what is the cross product (vector product) of A with each of those four vectors?
hence theta=0 degree
wbandersonjr said:This is not necessarily true. \Theta could be 180 also, or someother multiple of \pi.
But since sin\Theta equals zero, we know that the two vectors are parallel or antiparallel.
wbandersonjr said:Your way of answering is the direct way. This question is not so much about you computing a cross product as it is about you understanding that a cross product equal to zero means that the vectors are parallel. This is the concept that the question is reinforcing. You could do this by brute force, but that is time consuming and unnecessary if you understand the cross product well.