A massless and inextensible cord is wound round the circumference of a circular ring of mass M and radius R. The ring is free to rotate about an axis passing through its centre and perpendicular to its plane. A mass m is attached at the free end of the cord and is at rest. The angular speed of the ring when mass m has fallen through at height h is?

• A. v(2gh/R2)
• B. v(2mgh/MR2)
• C. v[2mgh/(M + 2m)R2]
• D. v[2mgh/(M + m)R2]