An airplane is flying 2000 miles at a planned speed of 600 mph. The flight will have an average headwind (flying directly into the wind) of w mph. The time (T) , in hours, of the flight is a function of the speed of the headwind w, in mph, can be modeled by the function T(w)=2000/600−w. The graph is shown below.

At what value of w does the graph have a vertical asymptote. Explain how you know and what this asymptote means in the context of this situation.