# A ring of diameter 1m is rotating about a central axis perpendicular to its diameter. It is rotating with a speed of 10rad/s. What force should be applied on it tangentially to stop it in exactly 3 rotations? Let the mass of the ring be 2kg.

Category: QuestionsA ring of diameter 1m is rotating about a central axis perpendicular to its diameter. It is rotating with a speed of 10rad/s. What force should be applied on it tangentially to stop it in exactly 3 rotations? Let the mass of the ring be 2kg.
Editor"> Editor Staff asked 1 year ago

A ring of diameter 1m is rotating about a central axis perpendicular to its diameter. It is rotating with a speed of 10rad/s. What force should be applied on it tangentially to stop it in exactly 3 rotations? Let the mass of the ring be 2kg.

(a) 10 N

(b) 25/3π N

(c) 50/3π N

(d) 12.5/3 N

I had been asked this question by my school principal while I was bunking the class.

Origin of the question is Kinematics of Rotational Motion about a Fixed Axis in portion System of Particles and Rotational Motion of Physics – Class 11
Select the correct answer from above options
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Editor"> Editor Staff answered 1 year ago

Right option is (b) 25/3π N

The best I can explain: Let w be the angular velocity & a be the angular acceleration.

Moment of inertia of the ring = MR^2

= 2*0.25 = 0.5kgm^2.