A conservator places an ultrasound transducer against a stone sculpture. At one point, the stone is 60 mm thick and ultrasound travels through it at 4000 m/s.
How long after the pulse is sent will the echo from the back surface return?
15 μs15\ \mu\mathrm{s}15 μs
30 μs30\ \mu\mathrm{s}30 μs
3000 μs3000\ \mu\mathrm{s}3000 μs
30 000 μs30\,000\ \mu\mathrm{s}30000 μs
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.