The position vector of 1 kg object is $\overrightarrow r = \left( {3\widehat i - \widehat j} \right)m$ and its velocity $\overrightarrow v = \left( {3\widehat j + \widehat k} \right)m{s^{ - 1}}$. The magnitude of its angular momentum is $\sqrt x$ Nm where x is ___________.
Answer (integer)
91
Solution
<p>$$\left| {\overrightarrow i } \right| = \left| {\overrightarrow r \times (m\overrightarrow v )} \right|$$</p>
<p>$= \left| {(3\widehat i - \widehat j) \times (3\widehat j + \widehat k)} \right|$</p>
<p>$= \left| { - \widehat i - 3\widehat j + 9\widehat k} \right|$</p>
<p>$= \sqrt {91}$</p>
About this question
Subject: Physics · Chapter: Rotational Motion · Topic: Centre of Mass
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