* The rock only experiences gravity: The rock is only influenced by gravity, causing it to accelerate downward. Its horizontal velocity remains zero.
* The ball has both vertical and horizontal velocity: The ball has an initial horizontal velocity. While gravity accelerates it downward, its horizontal velocity remains constant.
Result: The ball's final velocity is the vector sum of its horizontal and vertical velocities. Since it has a non-zero horizontal velocity, its final speed (magnitude of velocity) will be greater than the rock's final speed, which is only due to vertical acceleration.
