Find the numerical value of the terminal velocity vT. Do you think the value is realistic?

So far, our model only includes a constant driving force and drag. This is clearly an oversimplified model and not very realistic. We will now take more into account to make our model better. First and foremost, there is a physiological limitation to how fast a person can run. The driving force from the sprinter should therefore decrease with the velocity, so that there is a maximum velocity where the acceleration becomes zero even without air resistance. We set up a simplified force model which takes this into account. We introduce a driving force FD which has two contributions: a constant force F and a contribution that decreases with increasing speed, Fv = −fvv. The total driving force then becomes:

Reasonable values for the parameters are F = 400 N and fv = 25.8 Ns/m.