A force of 10 N acts at 60° to a 0.4 m long lever, measured from the pivot end. What is the moment about the pivot?
A4.00 Nm
B2.00 Nm
C3.46 Nm
D5.66 Nm
Answer & Solution
Correct answer: C. 3.46 Nm
1. Moment of force = Force × Perpendicular distance from pivot.
2. When the force makes an angle θ with the lever, only the perpendicular component F·sin θ contributes.
3. Given F = 10 N, lever length = 0.4 m, θ = 60°.
4. Perpendicular component = 10 × sin 60° = 10 × 0.866 ≈ 8.66 N.
5. Moment = 8.66 × 0.4 = 3.46 Nm.
6. Option A uses sin 90°, option B uses cos 60°; both ignore the geometry.
_Source: Selina Concise Physics ICSE Class 10, Ch 1 'Force' (icsehelp.com chapter extract)_
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