Question

A single force acts on a particle situated on the negative $x$-axis. The torque about the origin is in the positive $z$-direction. The force is

• A. In the negative $z$-direction
• B. In the positive $z$-direction
• C. In the positive $y$-direction
• D. In the negative $y$-direction

Answer 1

Answer: (D)

$\tau =\vec{r}\times \vec{F}$
$\Rightarrow +\hat{k}=[-\hat{i}]\times [\hat{F}]$
$\therefore \hat{F}=-\hat{j}$
So, force is in the negative $y$ direction.