For a science experiment, you would like to use the Doppler effect to double the perceived frequency of a harmonica, from the 261.7-Hz tone (middle C) that it emits, to 523.3 Hz (C_5 note). Which strategy will accomplish your goal more easily: move the observer move the harmonica Calculate the speed the harmonica must have in order for a stationary observer to hear 523.3 Hz. Express your answer to three significant figures and include appropriate units. Calculate the speed an observer must have in order to perceive a 523.3-Hz sound from a stationary harmonica that emits sound at 261.7 Hz. Express your answer to three significant figures and include appropriate units.