Question

A particle having mass $2kg$ is moving with velocity $(2\hat{i}+3\hat{j})m/s$. Find angular momentum of the particle about origin when it is at $(1,1,0)$.

• A. $2\hat{k}$
• B. $-\hat{k}$
• C. 0
• D. None of the above.

Answer 1

The correct option is A $2\hat{k}$

Position vector $\overrightarrow{r}=\hat{i}+\hat{j}$

Velocity $\overrightarrow{v}=2\hat{i}+3\hat{j}$ $m/s$

Mass $m=2kg$

Angular momentum $\overrightarrow{L}=m(\overrightarrow{r}\times \overrightarrow{v})$

$⟹\overrightarrow{L}=2\left[\right(\hat{i}+\hat{j})\times (2\hat{i}+3\hat{j}\left)\right]=2\hat{k}$