Question Detail
Question
A uniform meter rule with mass 75 g is suspended by a thread at the 75 cm mark and balanced by a weight W hanging from the 90 cm mark. Calculate W in grams.
Correct Answer
Option D is the correct answer.
Detailed Explanation
The rule's weight acts at its center (50 cm). Pivot at 75 cm. Clockwise moment due to rule's weight: 75 g × (75-50)=75×25=1875 g·cm. Anticlockwise moment due to W at 90 cm: W × (90-75)=W×15. Set equal: 1875 = 15W → W=125 g.
Hint
Use principle of moments about the suspension point.