Knowledge Organiser: Moments and Levers

Using slant distance instead of perpendicular distance: The distance in M = F × d must be the perpendicular distance from the pivot to the line of action of the force — not the length of the lever arm
Forgetting to convert weight: Convert mass to weight (W = m × g) before using in moment calculations — do not use kg values in the moment equation
Not stating the principle of moments: For 3+ mark balance questions, always state "sum of clockwise moments = sum of anticlockwise moments about the pivot"
Confusing moment and force: A larger force does not always produce a larger moment — a small force at a large distance can produce a bigger moment than a large force close to the pivot
Placing centre of mass wrongly for irregular shapes: Centre of mass is found by suspension method (hanging from different points) — it is not always at the geometric centre for irregular objects

M = Fd — "MOMENT = FORCE × DISTANCE":
Think of opening a door: you always push near the edge (far from pivot/hinges), not near the hinge. Maximum distance = maximum moment = easiest to open. Pushing near the hinge would be terrible — tiny distance, tiny moment.
Clockwise vs Anticlockwise — use a clock face: Imagine the object as a clock. Which way would the force rotate it — the same direction as clock hands (clockwise) or opposite (anticlockwise)? Label moments accordingly.
Principle of moments shortcut: "Clock = Anti-Clock" — the clockwise moments must equal the anticlockwise moments for balance.

Moments & Levers, Knowledge Organiser