Answer
When the rod is brought near the ball, the electrons in the ball are pushed to the opposite side of the ball. Then the positive charges in the side of the ball near the rod are attracted to the negatively charge rod, so the ball moves toward the rod.
When the rod touches the ball, electrons move from the rod to the ball. Then both the rod and the ball are negatively charged, so the ball flies away from the rod.
Work Step by Step
The charged rod could be negatively charged. When the rod is brought near the ball, the electrons in the ball are pushed to the opposite side of the ball. Then the positive charges in the side of the ball near the rod are attracted to the negatively charge rod, so the ball moves toward the rod.
When the rod touches the ball, electrons move from the rod to the ball. Then both the rod and the ball are negatively charged, so the ball flies away from the rod.
