What changes a ball velocity

Answer/Explanation: Speed and direction can change with time. When you throw a ball into the air, it leaves your hand at a certain speed. As the ball rises, it slows down. Then, as the ball falls back toward the ground, it speeds up again. When the ball hits the ground, its direction of motion changes and it bounces back up into the air.

electric field is a function of 1/r^2

yes, the force per unit charge for a point charge is inverse square law.