Graphs of x versus t and v versus t for the same nonuniform motion. (a) In the x versus t plot, the slopes of the tangents give the velocities. (b) In the v versus t plot, those slopes are plotted against t. Note that the horizontal tangent at t1 has zero slope.

Figure 2-9 Graphs of x versus t and v versus t for the same nonuniform motion. (a) In the x versus t plot, the slopes of the tangents give the velocities. (b) In the v versus t plot, those slopes are plotted against t. Note that the horizontal tangent at t₁ has zero slope.