A student is investigating moments using a simple balancing experiment with a metre rule. First, the student balances the metre rule, without any loads, on a pivot. He finds that it balances at the 49.4 cm49.4\text{ cm}49.4 cm mark. Load QQQ is a metal cylinder with a diameter slightly larger than the width of the metre rule, so that it covers the markings on the rule. Load QQQ is placed on the metre rule with its centre at the 76.8 cm76.8\text{ cm}76.8 cm mark. The rule does not slip on the pivot.
Explain how the student would ensure that the metre rule reading at the centre of QQQ is exactly 76.8 cm76.8\text{ cm}76.8 cm.
Calculate the distance between the pivot and the centre of load QQQ.
State and explain which end of the metre rule (the 0 cm0\text{ cm}0 cm end or the 100 cm100\text{ cm}100 cm end) will tilt downwards to touch the bench when load QQQ is placed on the rule.
245 exam-style questions on CIE IGCSE Physics 1.5 Forces, covering 1.5.1a Forces, resultant force and motion, 1.5.1b Load–extension graphs and the spring constant, 1.5.1c Friction and drag, 1.5.1d Force, mass and acceleration, 1.5.1e Motion in a circular path, 1.5.2a Moment of a force, 1.5.2b Principle of moments and equilibrium, and 1.5.3 Centre of gravity and stability. Each one has a worked solution and a mark scheme showing where the marks go.