JEE Advanced2006PhysicsRotational MotionActual
A solid sphere of radius R has moment of inertia J about its qeometrical axis. If it is melted into a disc of radius r and thickness t . If its moment of inertia about the tangential axis (which is perpendicular to plane of the disc), is also equal to I , then the value of r is equal to
Options
- A2 15 R
- B2 5 R
- C3 15 R
- D3 15 R
Correct answer
A. 2 15 R
Step-by-step solution
2 3 M R^2= 1 2 M r^2+M r^2 or 2 3 M R^2= 3 2 M r^2 r= 2 15 R