Kinematics Question 134
Question: The magnitude of a given vector with end points (4, ? 4, 0) and (? 2, ? 2, 0) must be
Options:
A) 6
B) $ 5\sqrt{2} $
C) 4
D) $ 2\sqrt{10} $
Correct Answer: D $ \vec{r}={{\vec{r}}_2}-{{\vec{r}}_1}=(-2\hat{i}-2\hat{j}+0\hat{k})-(4\hat{i}-4\hat{j}+0\hat{k}) $ therefore $ \vec{r}=-6\hat{i}+2\hat{j}+0\hat{k} $ $ |\vec{r}|=\sqrt{{{(-6)}^{2}}+{{(2)}^{2}}+0^{2}}=\sqrt{36+4}=\sqrt{40}=2\sqrt{10} $
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