A maintenance robot is inside an empty storage tank. Its ultrasound sensor is 6.8 m from wall P and 15.3 m from wall Q. The sensor sends a separate pulse directly towards each wall and detects the returning echo. The speed of ultrasound in the air is 340 m/s.
What is the difference between the return times of the two echoes?
0.025 s0.025\ \mathrm{s}0.025 s
0.090 s0.090\ \mathrm{s}0.090 s
0.130 s0.130\ \mathrm{s}0.130 s
0.050 s0.050\ \mathrm{s}0.050 s
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.