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The magnitude of the vector $\vec a = 3\hat i + 4\hat j$ is:
A$5$, since $|\vec a| = \sqrt{9 + 16} = 5$ on the chart
B$7$, the simple sum of magnitudes of components here
C$1$, by treating the unit vector formula incorrectly here
D$12$, the product of components on the school chart wrong
Answer & Solution
Correct answer: A. $5$, since $|\vec a| = \sqrt{9 + 16} = 5$ on the chart
$|\vec a| = \sqrt{3^2 + 4^2} = 5$.
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