Speedometer shows speed and odometer shows distance travelled, both relative to the surface on which the vehicle moves. Two conveyor-belts each of length L=500m are arranged along a line one after the other with a negligible gap. The belts are running in the same but unknown direction with constant speeds $u_1=20km/h$ and $u_2=30km/h.$ A toy car installed with both the instruments runs on the belts one after the other between two extremes spending $\tau =72s$ on them. The speedometer shows constant readings on each of the belts and the odometer shows a total reading of s=L=500m.