# A force of acts on O, the origin of the coordinate system. The torque about the point is : Option 1) Option 2) Option 3) Option 4)

As we learnt in

Torque -

$\underset{\tau }{\rightarrow}= \underset{r}{\rightarrow}\times \underset{F}{\rightarrow}$

- wherein

This can be calculated by using either  $\tau=r_{1}F\; or\; \tau=r\cdot F_{1}$

$r_{1}$ = perpendicular distance from origin to the line of force.

$F_{1}$ = component of force perpendicular to line joining force.

$given\; \; \; \vec{\tau }=\vec{r}\times \vec{F}$

$\vec{F}=-F\hat{k},\vec{r}=\hat{i}-\hat{j}$

$\dpi{100} =\hat{i}F-\hat{j}(-F)=F(\hat{i}+\hat{j})$

Option 1)

This is an incorrect option.

Option 2)

This is an incorrect option.

Option 3)

This is an incorrect option.

Option 4)

This is the correct option.

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