Answer
$10 \ N \ m$
Work Step by Step
The magnitude of torque is $|\tau|=|r \times F| =|r||F| \sin \theta....(1)$
The angle is acute, so $\theta =30^{\circ}$
Plug in the data. Equation (1) becomes:
$|\tau|=|r \times F| =(0.4)\times (50) \times \sin 30^{\circ}$
$\implies |\tau| \approx 10 \ N \ m$
