Introduction

As we saw in Chapter 2, Newton's second law of motion is only valid in inertial frames of reference. However, it is sometimes convenient to observe motion in non-inertial rotating reference frames. For instance, it is most convenient for us to observe the motions of objects close to the Earth's surface in a reference frame that is fixed relative to this surface. Such a frame is non-inertial in nature, because it accelerates with respect to a standard inertial frame as a result of the Earth's diurnal rotation. (Any accelerations of this frame owing to the Earth's orbital rotation about the Sun, or the Sun's orbital rotation about the galactic center, and so on, are negligible compared to that associated with the Earth's diurnal rotation.) Let us investigate motion observed in a rotating reference frame.