Moment of Inertia Calculation [closed]

A uniform disc has centre O, radius a and mass 2m. It is free to rotate in a vertical plane about a horizontal axis through O. A particle P of mass m is placed on the highest point of the rough edge of the disc and the system is slightly disturbed so that OP begins to rotate with the particle in contact with the edge. In the subsequent motion OP makes an angle θ with the upward vertical.

What will be the moment of inertia of the system about the centre of the disc. And how can we find the equation of rotational motion for the system.

closed as off-topic by Kyle Kanos, Danu, Qmechanic♦Apr 27 '15 at 19:24

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• Welcome to Physics.SE! Please note that this is not a homework help site. Please see this Meta post on asking homework questions and this Meta post for "check my work" problems. – 299792458 Apr 27 '15 at 18:29
• Please look up "mass moment of inertia" for basic shapes and add them up using the "parallel axis theorem". – ja72 Apr 27 '15 at 23:27

For disc $I=(2m*r*r)/2$
for small body $I=m*r*r$
• Disc MMOI is $I=\frac{m}{2} r^2$ – ja72 Apr 27 '15 at 23:29
• No, you have $I=(2m r^2)/2 = m r^2$. – ja72 Apr 28 '15 at 18:02