Gradient describes a rate - Online practice 2

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A straight segment on a distance-time model joins (3 s, 12 m) to (7 s, 28 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.