Question

A violinist places her finger so that the vibrating section of a 1.00g/m string has a length of 40.0cm , then she draws her bow across it. A listener nearby in a 20?C room hears a note with a wavelength of 60.0cm .

What is the tension in the string?

Answer 1

first find the frequency heard...

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speed of sound at 20 deg C = 343 m/s

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   f = v / ? = 343 /0.60   = 571.7 Hz

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Then... find the wavelength of the wave on the string:

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   ? = 2L = 2 * 0.40 = 0.80 meters

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Find the speed of the waves on the string:   speed = ? f = 0.80 * 571.7 =    457.3 m/s

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Then use:     speed² = Tension / ?     or

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   Tension = speed² *? = 457.3² * 0.001 =    209.2 Newtons