An atmospheric scientist monitors the vertical velocity, v m s−1v\text{ m s}^{-1}v m s−1, of a weather balloon during its initial ascent. The scientist plots a velocity-time graph for the first 12 seconds12\text{ seconds}12 seconds, as shown in Figure 1.
The equation for the straight line is v=at+uv = at + uv=at+u.
State the value of uuu from the graph in Figure 1.