A metal coin of mass 5 g and radius 1 c m is fixed to a thin stick A B of negligible mass as shown in the figure. The system is initially at rest. The constant torque, that will make the system rotate

Question

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

TestHub · Accepted Answer

As torque τ is constant. ω = τ I t τ = ω I t = 2 π n × 5 4 m r 2 t = 2 π × 25 × 5 4 × 5 × 10 - 3 × 1 × 10 - 2 2 5 = 196 × 10 - 7 ≈ 2 ⋅ 0 × 10 - 5 N m

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