Question 1.2: David walks east for 6 s at 2 ms^-1 then west for 2s at 1 ms...

i) David’s journey is illustrated below. (Figure 1.19)

ii) Speed–time graph   (Figure 1.20)

iii) Velocity–time graph   (Figure 1.21 )

The area between a velocity time graph and the x axis represents the change in position, that is the displacement.

When the velocity is negative, the area is below the axis and represents a displacement in the negative direction, west in this case.