Since the beginning of this series we've presented mechanics from one particular kinematic perspective. We observed some kind of motion, like an explosion, or the pinching of a water droplet, or the fall of an object, or the orbit of a planet, and we represented motion by plotting a length versus a time. We saw that the relationships between space and time could be understood by invoking the interplay of pairs of mechanical quantities, one impelling motion and the other impeding it. However, not all dynamics can easily be captured as the evolution of a length over time, and it is sometimes much more practical to use different pairs of kinematic variables. To each pair of kinematic variables corresponds a different perspective on the dynamics. Translating from one perspective to another is what we do in this episode.  We'll discuss cases where a speed is plotted against a distance, which is particularly useful to understand velocity profiles in hydrodynamics. We'll also talk about dispersion relations a perspective often used to study waves. Finally, we'll take some time connecting the spectral perspectives on turbulence, and the viewpoints that rather focus on coherent structures.   What we see in a particular situation is a combination of what is (the interplay of a pair of mechanical quantities) and of the perspective we've taken. Greater insight is reached by comparing what is perceived from different perspectives.