In Physics, we distinguish between wave motion and particle motion. Wave motion refers to the movement of a wave-like pattern from one location on the medium to another. When you view a water wave moving along the surface of water, you are observing wave motion. There is a very obvious movement of a collection of crests and troughs along the water surface. In the Simple Wave Simulator, there is a collection of crests and troughs moving through a rope; this is wave motion. But there are also three points on the rope that are colored red. When you observe the motion of these points, you are observing particle motion - the motion of particles of the rope. Describe the motion of these particles.