This claim isn’t true. This claim is trying to say that once force is being applied to Newton’s Cradle then it will forever stay in motion. However, from the excerpt we learn that this isn’t possible. As one of the balls are pushed, it is set into kinetic energy, and then that ball will hit another and send it into kinetic energy as well. However, not all of the kinetic energy is kept through this process, some of the energy is lost and converted into different forms such as sound energy. Therefore, it isn’t possible for Newton’s Cradle to stay in motion forever.