A tunnelling machine produces vibrations in limestone. The vibrations have a wavelength of 300 m and travel at 4800 m/s.
The vibrations pass into clay, where their speed is 1440 m/s. A row of electronic sensors measures the wavelength in the clay. A person nearby listens for the sound.
Which outcome is expected in the clay?
The person does not hear the sound and the sensors measure a wavelength of 90 m90\ \mathrm{m}90 m.
The person hears the sound and the sensors measure a wavelength of 90 m90\ \mathrm{m}90 m.
The person does not hear the sound and the sensors measure a wavelength of 300 m300\ \mathrm{m}300 m.
The person hears the sound and the sensors measure a wavelength of 1000 m1000\ \mathrm{m}1000 m.
112 exam-style questions on Edexcel GCSE Physics 4.3 Sound, ultrasound and infrasound, covering 4.3.1 Sound waves, vibrations and the human ear, 4.3.2 Ultrasound and infrasound, 4.3.3 Uses of ultrasound and infrasound, and 4.3.4 Sound waves passing between media. Each one has a worked solution and a mark scheme showing where the marks go.