Gradient describes a rate - Paper 2

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A straight segment on a distance-time model joins (5 s, 10 m) to (9 s, 30 m). Time is horizontal, recorded distance from a fixed start is vertical. Gradient is change in distance / elapsed time. The next segment is horizontal for 2 s. Interpret the stated model; a constant radial distance alone need not prove absolute stillness in a circular real-world path.