The torque, denoted by \( \mathbf{\tau} \), is calculated as the cross product of the position vector \( \mathbf{r} \) and the force vector \( \mathbf{F} \). The relationship is expressed as:
\[
\mathbf{\tau} = \mathbf{r} \times \mathbf{F}
\]
Given:
- Position vector \( \mathbf{r} = (1, 1, 1) \)
- Force vector \( \mathbf{F} = (1, -1, 1) \)
The torque component in the z-direction is determined by:
\[
\tau_z = r_x F_y - r_y F_x = 1 \times (-1) - 1 \times 1 = -2
\]
The magnitude of the torque in the z-direction is stated to be \( 1 \). Therefore, the final result is 1.