A small steel wire of diameter 1.0 mm is connected to an oscillator and is under a tension of 7.1 N. The frequency of the oscillator is 57.0 Hz and it is observed that the amplitude of the wave on the steel wire is 0.54cm. What is the power output of the oscillator, assuming that the wave is not reflected? If the power output stays constant but the frequency is doubled, what is the wave's amplitude?