A wire of mass 0.75 g and length 42 cm is stretched with a tension of 500 N. It is then placed near the open end of the tube shown in figure and stroked with a violin bow so that it oscillates at its fundamental frequency.

The general equation for the frequency is:

\(f=\frac{1}{2L}\sqrt{\frac{T*L}{m}}\)

where L is length (0.42m), T is tension (500N), m is mass (0.00075kg) and f is frequency (s^{-1})

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I'll leave you to plug in the numbers.