Motion in a Plane - Result Question 7

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9. If a vector $2 \hat{i}+3 \hat{j}+8 \hat{k}$ is perpendicular to the vector $4 \hat{j}-4 \hat{i}+\alpha \hat{k}$, then the value of $\alpha$ is

======= ####9. If a vector $2 \hat{i}+3 \hat{j}+8 \hat{k}$ is perpendicular to the vector $4 \hat{j}-4 \hat{i}+\alpha \hat{k}$, then the value of $\alpha$ is

3e0f7ab6f6a50373c3f2dbda6ca2533482a77bed:content/english/neet-pyq-chapterwise/physics/motion-in-a-plane/motion-in-a-plane—result-question-7.md (a) $1 / 2$

(c) 1

(b) $-1 / 2$

(d) -1

[2005]

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Answer:

Correct Answer: 9. (b)

Solution:

  1. (b) For two vectors to be perpendicular to each other

$\vec{A} \cdot \vec{B}=0$

$(2 \hat{i}+3 \hat{j}+8 \hat{k}) \cdot(4 \hat{j}-4 \hat{i}+\alpha \hat{k})=0$

$-8+12+8 \alpha=0$

$\alpha=-\frac{4}{8}=-\frac{1}{2}$