It is one hot summer day, so your mom tells you and your friends that you can have ice cream when the train comes through town. You and your friends decide to have a contest to see who will hear the train first. You decide to jump into the swimming pool and listen under water. You think water will help you feel and see the sound vibrations easier. Mary sits on a chair and decides that since air is thinner, the sound will travel faster through a thinner medium. Johnny puts his ear to the ground because he saw it in an old cowboy movie, and that is what the Indians did to hear the cowboys coming from a distance. Who is correct? Explain why that person is correct.