Moments · Year 12
In Year 12 you learn: moments.
A moment is the turning effect of a force about a point. For an object to stay still, the forces must balance and so must the moments. That is how we find the forces on beams, bridges, ladders and see-saws. It also shows where the centre of mass of a shape lies.
Key facts
- Take moments about a point where an unknown force acts, so that force drops out of the equation.
- Centre of mass of particles: x̄ = (Σmx)/(Σm). For laminas use areas, x̄ = (ΣAx)/(ΣA), and subtract any holes.
- A freely suspended object hangs with its centre of mass directly below the point of suspension.