Under what conditions is the torque about some location equal to zero? Make a sketch showing a situation in which the torque due to a single force about some location is 20 N m in the positive z...

Under what conditions is the torque about some location equal to zero?

Make a sketch showing a situation in which the torque due to a single force about some location is 20 N m in the positive

z direction, whereas about another location the torque is 10 N m in the negative z direction.