The equation for the vibration of a string, fixed at both ends vibrating in its third harmonic, is given by

y = (04 cm) sin[(0.314 cm^{−}^{1})x] cos[(600π s^{−}^{1})t]

(A) What is the frequency of vibration? (B) What are the positions of the nodes? (C) What is the length of the string? (D) What is the wavelength and the speed of two travelling waves that can interface to give this vibration?