1. Let's clarify the concept of moment (torque) about a point. 2. The moment of a force about a point is defined as the force multiplied by the perpendicular distance from the point to the line of action of the force. 3. This perpendicular distance is used because only the component of the force that causes rotation (i.e., perpendicular to the radius vector) contributes to the moment. 4. The distance along the line of action of the force does not cause rotation because it acts through the point or along the radius vector, producing no turning effect. 5. Therefore, when calculating the moment, we always use the perpendicular distance to the line of action of the force to find the effective lever arm. 6. Mathematically, the moment $M$ about a point is given by: $$M = F \times d_{\perp}$$ where $F$ is the magnitude of the force and $d_{\perp}$ is the perpendicular distance from the point to the force's line of action. 7. Using the distance along the line of action would not produce any rotation, so it is not used in moment calculations.