...
B.) Divide your graphs into segments and label each segment with the direction of the fan switch (forward or backward) during that segment.
Part 3
...
– Challenge
In Part 2 we assumed that the best way to travel is to speed up for half the trip and then slow down for the second half. This gives your craft the greatest controllable speed (assuming you don't want to hit something at your destination to stop), but it also requires you to decelerate much earlier than if you just turned off the fan and coasted for a while at some intermediate speed. Assuming you want to minimize the time to your destination, what is the best way to use the fan?