A boy is seated in a revolving chair revolving at an angular speed of 120 revolutions per minute. Two heavy balls form part of the revolving system and the boy can pull the balls closer to himself or may push them apart. If by pulling the balls closer, the boy decreases the moment of inertia of the system from 6 kg-m 2 to 2 kg-m 2 , what will be the new angular speed?

A boy is seated in a revolving chair revolving at an angular speed of 120 revolutions per minute. Two heavy balls form part of the revolving system and the boy can pull the balls closer to himself or may push them apart. If by pulling the balls closer, the boy decreases the moment of inertia of the system from 6 kg-m² to 2 kg-m², what will be the new angular speed?

Given:

Angular speed (ω₁) = 120 rpm

Moment of inertia (I₁) = 6 kg-m²

Moment of inertia (I₂) = 2 kg-m²

New angular speed (ω₂) =?

Since two balls are inside the system

Hence, total external torque = 0

Therefore,

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