So one day Karel was casually riding the Prague metro and saw an information panel about trams. It said that the power of a tram car increased tenfold in the last decades. How many times did the maximum speed increase, assuming their weight didn't change and the resistive force are proportional to the second power of tram's velocity? In other words, we want to know the value of k = v₁/v₀, where v₀ is the original maximum speed and v₁ is the current one.