Halliday, Resnick & Walker — Waves–I: Problem Problem_58

In Fig. 16.19, a string, tied to a sinusoidal oscillator at \(P\) and running over a support at \(Q\), is stretched by a block of mass \(m\). Separation \(L = 1.20 \text{ m}\), linear density \(\mu = 1.6 \text{ g/m}\), and the oscillator frequency \(f = 120 \text{ Hz}\). The amplitude of the motion at \(P\) is small enough for that point to be considered a node. A node also exists at \(Q\). (a) What mass \(m\) allows the oscillator to set up the fourth harmonic on the string? (b) What standing wave mode, if any, can be set up if \(m = 1.00 \text{ kg}\)?