From heaven to earth

Chef has been working in a restaurant which has $N$ floors. He wants to minimise the time it takes him to go from the $N$-th floor to ground floor. He can either take the elevator or the stairs. The stairs are at an angle of $45$ degrees and Chef's velocity is $V_1$ m/s when taking the stairs down. The elevator on the other hand moves with a velocity $V_2$ m/s. Whenever an elevator is called, i