# E-note and Doppler effect

Classical Mechanics Level 3

The high “E-note” string on a guitar has a linear mass density of $$\mu .$$ It is tightened between two fixed points a distance $$L$$ apart to a tension of $$T.$$ A performer on a stage plays this E-note at the same time as a fast spectator rushes toward the stage at high speed. What is the minimum speed the spectator must go so that the frequency he observes is above the human range of hearing, $$f_{max} ?$$ Please express your answer in terms of numerical constants and any of the following: $$\mu , L, T, f_{max}$$ and the speed of sound in air, $$v.$$

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