A set of hollow pipes are closed on one end by immersing them in water, leaving only one open end. The lengths of the pipe above the water differ by 20.0 cm. Determine the beat frequency for a pipe with a length of 2.0 m above the water and i) a longer pipe ii) a shorter pipe. (Consider waves with fundamental frequency only)

A childhood game involves tying light gauge polythene papers together and attaching a small mass on one end of the polythene paper string. The mass is swung in a circle using the polythene paper string emitting sound. Suppose a child is rotating a mass at 163 rpm when an observer hears a 0.50 Hz frequency due to the presence of another child rotating a second mass. i) determine two possible rotational frequencies in RPM for the second mass. ii) When the rotational speed of the second mass is decreased, the beat frequency decreases to 0.40 Hz. Which of the values determined in i) is the true rotational frequency of the second mass? 

Two violinists are tuning their equipment to simultaneously play a note of wavelength 773 mm. However, one piece of equipment produces a note of wavelength 767 mm, which is different from the desired wavelength. Determine the beat frequency an observer will detect from the two pieces of equipment played together. 

Suppose you have a pair of identical tuning forks, producing sound waves at a frequency of 523 Hz. Holding one of the tuning forks steady, you let the other fall from a 15-meter-high ledge. Ignoring air resistance determine the total beats you will hear before the plummeting tuning fork impacts the surface.