A tuning fork A vibrates at 320 Hz. When fork A is sounded together with another fork B, 7 beats are heard per second.
(a) Calculate the two possible frequencies of fork B.
(b) A small piece of wax is then added to one prong of fork B and the pair is struck again with fork A. Beats now disappear completely. Determine the original frequency of fork B and explain the reasoning behind your choice.