What is a moment? Moments Learning Outcomes C: Define the principle of moments B: Use moments to solve simple problems A/A*: Apply principle of moments to investigation. Principle of moments Moment = force x perpendicular distance Moment = Fd sum of anticlockwise moments = sum clockwise moments F1 x d1 = F2 x d2 sum of anticlockwise moments = sum clockwise moments F1 x d1 = (F2 x d2) + (F3 x d3) 1. By taking moments about point S, show that the weight, W, of the rod is 0.12N 2. What is the tension in the supporting thread? 5 6 A couple is two equal forces which act in opposite directs on an object but not through the same point so they produce a turning effect. Moment of Couple = Fs 7 Horizontal Component Vertical Component 8