In which of the following situations is there observational evidence for significant interaction between two objects? how can you tell?

1 .a communications satellite orbits the earth.
2. a ball bounces off a wall with no change in speed.
3. a space probe travels at constant speed toward a distant star.
4. a baseball that was hit by a batter flies toward the outfield.
5. a charged particle leaves a curving track in a particle detector.