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Rotational Mechanics — Physics STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 SciencePhysicsRotational Mechanics1 Mark
Question
A particle moves with a constant velocity parallel to the X-axis. Its angular momentum with respect to the origin:
  1. Is zero.
  2. Remains constant.
  3. Goes on Increasing.
  4. Goes on decreasing.
✓

Answer

  1. Remains constant.

Explanation:

For angular momentum. we have:

$\overrightarrow{\text{L}}=\text{m}\Big(\overrightarrow{\text{r}}\times\overrightarrow{\text{v}}\Big)$

$\overrightarrow{\text{v}}=\text{v}\hat{\text{i}}$ and $\overrightarrow{\text{r}}=\text{x}\hat{\text{i}}+\text{y}\hat{\text{j}}$

So, $\overrightarrow{\text{L}}=-\text{mvy}\hat{\text{k}}$

m, v and y are constant; therefore, angular momentum remains constant.

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