We now develop a method to refer to reference frames in relative motion. In summary, all discussion of relative motion must define the reference frames involved. In this case, the solar system is the reference frame. We can expand our view of the motion of the person on the train and say Earth is spinning in its orbit around the Sun, in which case the motion becomes more complicated. If you say a person is sitting in a train moving at 10 m/s east, then you imply the person on the train is moving relative to the surface of Earth at this velocity, and Earth is the reference frame. In most examples we have examined so far, this reference frame has been Earth. When we say an object has a certain velocity, we must state it has a velocity with respect to a given reference frame. To discuss relative motion in one or more dimensions, we first introduce the concept of reference frame s. To explore this idea further, we first need to establish some terminology. Your velocity relative to the other train is 5 m/s west. However, if another train passes you at 15 m/s east, your velocity relative to this other train is different from your velocity relative to the ground. If you’re riding in a train moving at 10 m/s east, this velocity is measured relative to the ground on which you’re traveling. Analyze one-dimensional and two-dimensional relative motion problems using the position and velocity vector equations.Draw the position and velocity vectors for relative motion.Write the position and velocity vector equations for relative motion.Explain the concept of reference frames.By the end of this section, you will be able to:

Relative motion definition