Newton would not agree with that explanation, and he would tell my brother to go to his room. Then Newton would turn to me and explain:
Once the soccer ball is in motion, it will continue moving in a straight line with constant speed, until external forces change its motion. (Newton's #1 Law of Motion).
There are external forces on the soccer ball after the kick: gravity, air resistance, and scraping through grass.
Gravity has no effect on its horizontal motion. But air resistance and scraping through grass are both friction ... they both rob kinetic energy from the ball. Once the kinetic energy of the ball is all gone, it doesn't move any more. An observer looking at the ball and measuring its motion would write in his notebook "The ball has stopped." .
