-vx = 0 and vy=0 but also when the force 'a' which initially had a value of 0.1 [double a = 0.1] gets its value reduced and reaches 0.0 at the same time that vx and vy get the value of 0?

Is there a formula to be used to gradually reduce the speed of a ball in motion and then stop the ball at a certain point and time?