A sphere rolling on a horizontal rough surface Collides elastically with a smooth vertical wall, as shown in Fig. State which of the following statements is true or false. centre of mass gets reversed. b. Angular momentum of the sphere about the point of contact with the wall is conserved. c. Angular momentum of the sphere about a stationary point on the horizontal surface is conserved. d. Just after collision the point of contact with the horizontal surface is moving towards the wall. e. After collision the friction force acts on the sphere such that it decreases the linear speed and increases the angular speed. f. Finally, when the sphere starts rolling, it is moving away from the wall.