AIIMS2002Physics-Vectors
AIIMS 2002 Physics Dot Product MCQ Question
Type: MCQ-numerical-Medium-Class 11
If vectors P = ai + aj + 3k and Q = ai - 2j - k are perpendicular to each other, then the positive value of a is
A
3
B
1
C
2
D
0
Correct Answer
Option A
Detailed Explanation
Vector P = ai + aj + 3k and vector Q = ai - 2j - k. If two vectors are perpendicular to each other, then P·Q = 0 or (ai + aj + 3k)·(ai - 2j - k) = 0 or a^2 - 2a - 3 = 0. Solving this quadratic equation, we get a = 3 or -1. Therefore positive value of a is 3.
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