Kinematics Question 451

Question: Which of the following its a unit vector?

Options:

A) $ \hat{i}+\hat{j} $

B) $ \cos \theta \hat{i}-\sin \theta \hat{j} $

C) $ \sin \theta \hat{i}+2x\cos \theta \hat{j} $

D) $ \frac{1}{\sqrt{3}}(\hat{i}+\hat{j}) $

Show Answer

Answer:

Correct Answer: B

Solution:

[b] Let $ \vec{A}=\cos \theta \hat{i}-\sin \theta \hat{j} $
$ \therefore $

$ |\vec{A}|=\sqrt{{{\cos }^{2}}\theta +{{\sin }^{2}}\theta }=1 $

Therefore, its a unit vector.



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