What is the value of the resultant turning moment about the pivot at the instant when the rule is horizontal?

The correct answer to this question is 160NCM anticlockwise. This question deals with forces and moment. The metric rule of this question is uniform in the weight act. This uniformity creates an anticlockwise moment. The 4.0N weight is downward at one end, creating a clockwise moment.

This resultant moment equals to (4.0 x (100-60) x 10) - (16.0 x 0.1), which equals 160nm. The resulting moment is not able to be zero. In this question, the rule is an instant, which is why it is unable to be zero. If the rule was remaining horizontal at equilibrium, then zero would be a possibility.