Balancing a metre rule on a pivot is one of the most common Question 1 experiments in Paper 6. Here an object Q sits on the 70.0 cm mark and known loads balance it from the other side. Watch the set-up built step by step, with the variables and the graph beside it, then build it yourself and check it against the mark points.
Past-paper referenceOriginal experiment, wording and figures, written in the style of Cambridge IGCSE Physics 0625 Paper 6 (Alternative to Practical). It is not copied from a past paper. The “what the examiners said” notes are our paraphrase of the Principal Examiner Reports for Teachers.
Practise next: 0625/62 February/March 2024, (Question 1: the mass of a metre rule by a balancing method, with a gradient) · official past papers
Practise next: 0625/61 October/November 2025, (Question 1: balancing an object Q with two loads) · official past papers
Practise next: 0625/63 May/June 2023, (Question 1: the mass of a metre rule and its centre of mass) · official past papers
Examiner reports used: 0625 June 2023 (Papers 61 and 63), November 2023 (Paper 61), March 2024 (Paper 62), June 2025 (Paper 63) and November 2025 (Paper 61).
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What a full-mark diagram shows
A narrow pivot
The metre rule rests on a narrow pivot at the balance point of the empty rule, found first with no loads on it.
Centred loads
Object Q has its edges the same distance either side of the 70.0 cm mark. The centre of each load is the average of its two edges.
Balanced by the tip test
The load sits midway between where the rule just tips one way and where it just tips the other way.
Distances to the nearest mm
d is measured from the centre of the load to the pivot, for example 36.0 cm, never the diameter or radius of the load.
Habits the examiner reports keep asking for
Describe the tip test, not a check that the rule is horizontal, when asked how you know it is balanced.
Read both edges of the load and take the average. The load hides the scale under its centre.
Do not stick clay on the rule to make it balance: it changes the mass of the rule. Measure from the real balance point instead.
Draw the line the plots show: a smooth curve for d against W, a straight line for d against 1/W, with a large gradient triangle.
Give a unit and 2 or 3 significant figures for every calculated answer.