To determine the minimum velocity needed for a ball to ascend a step without slipping, consider the momentum equilibrium at the contact point between the ball and the step. The condition of no slipping implies that the velocity of the contact point remains zero during motion. Analyzing the collision phase reveals that angular momentum is conserved, which helps calculate the angular velocity after the collision. In the post-collision phase, mechanical energy conservation applies, as only gravity does work on the system. Applying these principles will lead to the required minimum velocity for the ball to successfully navigate the step.