Single Choice

Of the vectors given below, the parallel vectors are $$\vec{A}=6\hat{i} +8\hat{j}$$ $$\vec{B}=210\hat{i}+280\hat{k}$$ $$\vec{C}=5.1\hat{i}+6.8\hat{j}$$ $$\vec{D}=3.6\hat{i}+8\hat{j}+48\hat{k}$$

A$$\vec{A}$$ and $$\vec{B}$$
B$$\vec{A}$$ and $$\vec{C}$$
Correct Answer
C$$\vec{A}$$ and $$\vec{D}$$
D$$\vec{C}$$ and $$\vec{D}$$

Solution

Vectors A and C are parallel to each other due to the ratio of both's i and j components are same.
Also their unit vector is same i.e. unit vector of A is $$\dfrac{6\hat i+8\hat j}{\sqrt{6^2+8^2}}$$=\dfrac{3}{5} \hat i + \dfrac{4}{5} \hat j$$
Unit vector of C is $$\dfrac{5.1\hat i+6.8\hat j}{\sqrt{5.1^2+6.8^2}}$$=\dfrac{3}{5} \hat i + \dfrac{4}{5} \hat j$$


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