Changing velocity

Step 5

Now extend the idea of accumulations to acceleration accumulating velocity: it may be better to resist the temptation to place the velocity vectors tip to tail at the this stage to avoid any suggestion of representing a track that is followed.

Again, you can look into the detail of the reasoning with arrows here.

Then, as a second step, link both accumulations, one after another, to predict the track of a journey.

This introduces the second tautology of kinematics ('acceleration tells velocity how to change', again in its natural two-dimensional environment).