Find the torque about the origin when a force of $3\widehat{\mathrm{j}}\mathrm{N}$  acts on a particle whose position vector is $2\widehat{\mathrm{k}}\mathrm{m}.$

The torque about the origin can be expressed as:

$\tau = \overrightarrow{\mathrm{r}}\times \overrightarrow{\mathrm{F}}\text{,}$

Where $\overrightarrow{\mathrm{r}}$is the position vector and, $\overrightarrow{\mathrm{F}}$ is the force acting.

Here, $\overrightarrow{\mathrm{r}}=2\hat{\mathrm{k}}\mathrm{m} \text{and}\stackrel{ \to }{ \mathrm{F}}=3\hat{\mathrm{j}}\mathrm{N}\text{.}$

Torque $\mathbf{=}\mathbf{2}\stackrel{\mathbf{ }\mathbf{^}}{\mathbf{k}}\mathbf{\times }\mathbf{3}\hat{\mathbf{j}}\mathit{N}\mathit{m}\mathbf{=}\mathbf{-}\mathbf{6}\hat{\mathbf{i}}\mathit{N}\mathit{m}$