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A uniform metre rule of mass 100 g is pivoted at the 40 cm mark. Where must a 60 gf weight be hung to keep it horizontal?
Original Khojo Papers practice question — not from a past board paper.
Answer
At the 23.33 cm mark, that is 16.67 cm from the pivot on the shorter side.
No citable source has been recorded for this record. Treat it as practice material, not as fact.
Explanation
The weight of the rule, 100 gf, acts at its centre, the 50 cm mark, which is 10 cm from the pivot, giving a clockwise moment of 1000 gf cm. The 60 gf must give an equal anticlockwise moment, so its distance is 1000 ÷ 60 = 16.67 cm on the other side, at the 23.33 cm mark.
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