If we assume that the sprinter is only affected by FD, what is the maximum velocity (the terminal velocity) now? We ignore air resistance in this part of the task.

We continue to improve our model. At the start of the race, the sprinter is in s crouched position (based on the starting block) and accelerates quickly. In this part of the race, the cross-section of the sprinter is smaller, and the driving force is greater than later in the race. We assume that this phase lasts for a time tC, and we expect the drive to decrease gradually as the sprinter goes from a crouched position to a more upright position.

We take this into account by assuming that the driving force has a time-dependent component that can be described by an exponential function that depends on the time t and the characteristic time tC: