Does increasing the speed of a ball on a string change force on string?

Yes, increasing the speed of a ball on a string does change the force on the string. As the speed of the ball increases, the centripetal force required to keep the ball moving in a circular path also increases. This force is proportional to the square of the speed, meaning that even a small increase in speed can significantly raise the tension in the string. Thus, the force exerted on the string increases with higher speeds.