An underwater survey pod is stationary between two opposite rock walls, A and B, in a flooded cavern. It sends an ultrasound pulse straight towards each wall.
The echo from wall A returns after 0.085 s and the echo from wall B returns after 0.137 s. The speed of ultrasound in the water is 1460 m/s.
The pod is then moved along the line between the walls until it is midway between them.
Calculate the distance the pod moves.
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.