Thanks for your reply! One question: how is the inelastic impact in the vertical direction? Is it not an angle to vertical since the incline is slanted? Many thanks!No, you are missing the point. The sudden loss of speed on hitting the horizontal surface in the given solution has nothing to do with friction. It is because of the inelastic impact in the vertical direction. And making it elastic doesn’t help; it would bounce, but the vertical momentum and energy it had on the ramp still does not contribute to the horizontal speed after impact.