Final answer:
A moment about a point is defined as the torque applied at that point, which can be calculated using the equation T = rF sin(θ), representing the twisting effectiveness of a force.
Step-by-step explanation:
A moment about a point is defined as the torque applied at that point, not merely the force applied. Torque is a measure of the turning or twisting effectiveness of a force and is a critical concept in mechanics. It depends on the magnitude of the force applied, the direction of the force, the distance of the force application point from the pivot point (radius), and the angle between the force and the position vector (from the pivot point to the point of force application).
To calculate torque (T), the equation T = rF sin(θ) is used, where r represents the radius, F the force, and θ the angle between the force and the displacement vector from the pivot point to the point where the force is applied. When a force is applied perpendicular to the radius, as is often the case in physics problems, the sine function becomes maximized (sin(90 degrees) = 1), and the torque is then simply T = Fr.