Scientists use detectors to record infrasound produced by volcanic eruptions.
The infrasound from one eruption has a frequency of 2.5 Hz.
The speed of sound in air is 340 m/s.
State why this sound is described as infrasound.
Calculate the wavelength of the infrasound in air.
A detector is 51 km from the volcano.
Calculate the time taken for the infrasound to travel from the volcano to the detector.
Some of the infrasound passes into the ground, where the speed of sound is greater.
State what happens to the wavelength of the infrasound.