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A spanner of length 40 cm needs a force of 140 N to unscrew a nut. To unscrew the same nut, what spanner length is needed if only 40 N is applied?
A11.4 cm
B140 cm
C100 cm
D56 cm
Answer & Solution
Correct answer: B. 140 cm
1. The same nut needs the same moment: F₁ x d₁ = F₂ x d₂.
2. Substitute: 140 x 40 = 40 x d₂, so 5600 = 40 x d₂.
3. d₂ = 5600 / 40 = 140 cm.
4. Rule out 11.4 cm: that divides distance by force ratio backwards, giving too short a handle.
_Source: Samacheer Kalvi (TN SCERT) Class 10 Science, Unit 1 "Laws of Motion", p.21_
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