15. A small ball of mass \( m \) is placed in a circular tube of negligible width, mass \( M \) and radius \( R \) which is kept on a horizontal plane in gravity free space. Friction is absent between tube and ball. Ball is given a velocity \( v _{0} \) as shown. Then,
(A) Path of ball from centre of mass of system (ball + tube) will be circular.
(B) Path of ball from centre of mass of system (ball + tube) will be elliptical
(C) Radius of curvature of ball at the time of projection of ball is \( \frac{M R}{m+M} \)
(D) Normal foree between tube and ball if \( M=2 m \), at the time of projection of ball is \( \frac{2 m V_{0}^{2}}{3 R} \)
