Putting Numbers on Motion

Five parts on describing movement precisely, which the first physics track needed and did not have. It opens on a car that averages 50 km/h without ever driving at 50 — not a paradox but two honest answers, because average speed covers a whole journey including every stop while a speedometer covers a moment. The second part adds direction and finds that a full lap of a track leaves a real distance and a real speed beside an average velocity of exactly zero, which is what separates a vector from a scalar. The third takes on the mistake nearly everyone makes first: reading a distance-time graph as a picture of the route, so a rising line becomes a hill and a flat line becomes level ground, when flat actually means stopped. The fourth narrows a familiar word — braking is acceleration, cornering at a steady speed is acceleration, and a train at a constant 300 km/h has none at all. The last swaps the vertical axis to velocity, where the gradient gives acceleration and the space under the line gives distance, because velocity multiplied by time is what finding an area does.