Question

Find the torque about point O and A.
$\hat{F}=5\sqrt{3}\hat{i}+5\hat{j}$

Answer 1

Torque about point O, $\overline{\tau }=\overline{r_0}\times \overline{F},\overline{r_0}=\hat{i}+\hat{j},\overline{F}=5\sqrt{3}\hat{i}+5\hat{j}$
$\hat{\tau }=(\hat{}+\hat{j})\times (5\sqrt{3}\hat{i}+5\hat{j})=5(1-\sqrt{3})\hat{k}$
Torque about point A, $\overline{\tau }=\overline{r_a}\times \overline{F},\overline{r_a}=\hat{j},\overline{F}=5\sqrt{3}\hat{i}+5\hat{j}$
$\overline{\tau }=\hat{j}\times (5\sqrt{3}\hat{i}+5\hat{j})=5(-\sqrt{3})\hat{k}$