JEE MAIN - Physics (2022 - 28th June Morning Shift - No. 22)
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 ___________.
คำตอบ
91
คำอธิบาย
$$\left| {\overrightarrow i } \right| = \left| {\overrightarrow r \times (m\overrightarrow v )} \right|$$
$$ = \left| {(3\widehat i - \widehat j) \times (3\widehat j + \widehat k)} \right|$$
$$ = \left| { - \widehat i - 3\widehat j + 9\widehat k} \right|$$
$$ = \sqrt {91} $$