Why is the following situation impossible? A student is listening to the sounds from an air column that is 0.730 m long. He doesn’t know if the column is open at both ends or open at only one end. He hears resonance from the air column at frequencies 235 Hz and 587 Hz.

A phone cord is 4.89 m long. The cord has a mass of 0.212 kg. A transverse wave pulse is produced by plucking one end of the taut cord. That pulse makes four round trips (down and back) along the cord in 0.666 s. What is the tension in the cord? Hint: Four round trips is a total distance of eight lengths of the cord.

Two loudspeakers on a concert stage are vibrating in phase. A listener is 52.5 m from the left speaker and 24.0 m from the right one. The listener can respond to all frequencies from 20 to 20 000 Hz, and the speed of sound is 343 m/s. What are the two lowest frequencies that can be heard loudly due to constructive interference?

Suppose the strings on a violin are stretched with the same tension and each has the same length between its two fixed ends. The musical notes and corresponding fundamental frequencies of two of these strings are G (196.0 Hz) and E (659.3 Hz). The linear density of the E string is 7.74 x 10-4 kg/m. What is the linear density of the G string?

Dolphins of the open ocean are classified as Type II Odontocetes (toothed whales). These animals use ultrasonic "clicks" with a frequency of about 55 kHz to navigate and find prey.  Suppose a dolphin sends out a series of clicks that are reflected back from the bottom of the ocean 90 m below. How much time elapses before the dolphin hears the echoes of the clicks? (The speed of sound in seawater is approximately 1530 m/s.) What is the wavelength of 55 kHz sound in the ocean?