Two strings with linear density of 5.0 g/m are stretched over pulleys and adjusted to have vibrating lengths of 50 cm. The block attached to string X has a mass of 20 kg. The block attached to string Y has mass M. Listeners hear a beat frequency of 2.0 Hz when string X is excited at its fundamental frequency and string Y at its third harmonic.
A. Find the speed, wavelength, and frequency of the wave on string X.
B. Find the wavelength of the wave on string Y.
C. What are possible frequencies of the wave on string Y?
D. What is one possible value for the mass M?