A particle in a magnetic field travels in a straight line. The force (in Newtons) acting upon it is given by the function

F(s) = square root of (s) −s^2, where s = f(t), the position of the particle in meters, changes with time t. At what rate is the force changing with respect to time at a time T for which the particle is at position s = 1 and has velocity 4 m/s.

Please explain this prob and how to do it!