Physics

Physics

Problem

A string fixed at both ends has consecutive standing wave modes for which the distances between adjacent nodes are 18 cm and 16 cm, respectively. (a) What is the minimum possible length of the string? (b) If the tension is 10 N and the linear mass density is 4 g/m, what is the fundamental frequency?
Intuitive explanation

The key insight is that standing wave modes are numbered by how many half-wavelengths fit in the string's fixed length LL. For mode nn, the distance between adjacent nodes is λn/2\lambda_n/2, so you can write two equations relating the string length to consecutive modes. Since LL stays the same, you can eliminate it and solve for which modes you're observing, then find the actual string length.

Intuitive explanation

The key insight is that standing wave modes are numbered by how many half-wavelengths fit in the string's fixed length LL. For mode nn, the distance between adjacent nodes is λn/2\lambda_n/2, so you can write two equations relating the string length to consecutive modes. Since LL stays the same, you can eliminate it and solve for which modes you're observing, then find the actual string length.

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