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A metal coin of mass 5 g and radius 1 cm is fixed to a thin stick AB of negligible mass as shown in the figure. The system is initially at rest. The constant torque, that will make the system rotate about AB at 25 rotations per second in 5s, is close to : 1 cm A B

1. 7.9 × 10 –6 Nm
2. 4 .0 × 10 –6 Nm
3. 2.0 × 10 –5 Nm
4. 1.6 × 10 –5 Nm CAREER POINT CAREER POINT , CP Tower, IPIA, Road No.1, Kota (Raj.), : 0744-6630500 | www.ecareerpoint.com Email: info@cpil.in Page # 4 JEE Main Online

Correct answer: 2.0 × 10 –5 Nm

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