6. 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 m, linear density 1.6 g/m, and the oscillator frequency 120Hz. The amplitude of the motion at P is small enough for that point to be considered as a node. A node also exits at Q. (a) what mass m allows the oscillator to set up the fourth harmonic on the string? (b) What standing mode, if any, can be set up if m= 1 kg. 6. 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 m, linear density 1.6 g/m, and the oscillator frequency 120Hz. The amplitude of the motion at P is small enough for that point to be considered as a node. A node also exits at Q. (a) what mass m allows the oscillator to set up the fourth harmonic on the string? (b) What standing mode, if any, can be set up if m= 1 kg. 6. 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 m, linear density 1.6 g/m, and the oscillator frequency 120Hz. The amplitude of the motion at P is small enough for that point to be considered as a node. A node also exits at Q. (a) what mass m allows the oscillator to set up the fourth harmonic on the string? (b) What standing mode, if any, can be set up if m= 1 kg.