A disc is free to rotate about an axis passing through its centre and perpendicular to its plane. The moment of inertia of the disc about its rotation axis is I. A light ribbon is tightly wrapped over it in multiple layers. The end of the ribbon is pulled out at a constant speed of u. Let the radius of the ribboned disc be R at any time and thickness of the ribbon be `d (lt lt R)`. Find the force (F) required to pull the ribbon as a function of radius R.

A disc is free to rotate about an axis passing through its centre and

1.	A disc is free to rotate about an axis passing through its centre and perpendicular to its plane. The moment of inertia of the disc about its rotation axis is I. A light ribbon is tightly wrapped over it in multiple layers. The end of the ribbon is pulled out at a constant speed of u. Let the radius of the ribboned disc be R at any time and thickness of the ribbon be `d (lt lt R)`. Find the force (F) required to pull the ribbon as a function of radius R.
Answer» Correct Answer - `F = (Idu^(2))/(2piR^(4))`

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