Consider an object which the net force is a resistive force proportional to the square of its speed. For example: assume that the resistive force acting on a speed skater is f=-kmv^2, where k is a constant and m is the skater's mass. The skater corsses the finish line of a straight-line race with speed v(i) and the slows down by coasting on his skates. Show that his speed at time "t", any time after the finish line is equal to Vf=Vi/(1+Vi*k*t). Do i need to do a diff eq for this?