Let the vector position of the object in the (x-y) plane be
[tex]\vec{r} = x \hat{i} + y \hat{j}[/tex]
The applied force is
[tex]\vec{f} = -12.5 \hat{i}
[/tex]
By definition, the applied torque is
[tex]\vec{T} = \vec{r} \times \vec{f} = (x\hat{i} + y\hat{j}) \times (-12.5y \hat{i}) = 12.5\hat{k}[/tex]
Answer: [tex]12.5y \, \hat{k}[/tex]
