HKDSE Physics Chapter 3 Quick Guide: Moment of Force & Equilibrium Torque (Moment of a Force): The turning effect of a force, calculated by multiplying the applied force by the perpendicular distance from the pivot. Principle of Moments: For an object in rotational equilibrium, the sum of clockwise moments equals the sum of anticlockwise moments about any point. Static Equilibrium: Requires both translational equilibrium (no net force) and rotational equilibrium (no net torque) simultaneously. Centre of Gravity (CG): The specific point through which the entire weight of an object appears to act. Stability & Toppling on an Inclined Plane: An object will topple if the vertical line passing through its Centre of Gravity falls outside its base of support. Lowering the CG and widening the base increases stability. Taught by Billy Sir, CUHK Physics Master. Get 5* in your HKDSE Physics exam.*