Answer
The correct answer is:
(f) 3 and 4
Work Step by Step
Only force 3 produces a clockwise torque. The other three forces produce a counterclockwise torque.
The torque is $\tau = r\times F$, where $r$ is the smallest distance between the force vector and the axis, and $F$ is the perpendicular component of the force vector.
Since force vector 3 has a magnitude that is about double the other three forces, we need to find the force vector that has a smallest distance $r$ to the axis that is about double of force vector 3's smallest distance $r$ to the axis.
Vector 4 seems to have a smallest distance $r$ to the axis that is about double that of vector 3.
The correct answer is:
(f) 3 and 4
