A hemispherical shell of mass m and radius R is hinged at point O and placed on a horizontal surface MN as shown in the figure. A ball of mass m moving with velocity u inclined at an angle
θ
=
tan
−1
(
1
2
)
strikes the shell at point A (as shown in the figure) and stops. What is the minimum speed u if the given shell is to reach the horizontal surface OP ?
