This question uses the graph in Figure 4 that shows the velocity, v, versus the time, t, for a 100 metre runner. 10 8 160 v (ms-) 4 2 -2 4 6 8 10 12 t(s) Figure 4 velocity v, versus time, t, for a 100 metre runner. a. Provide a series of estimates for the runner's acceleration t = 1.5 s by approximating the curve as a straight line between the following intervals: t = 1.5 s and t = 6 s t = 1.5 s and t = 4.5 s