An oceanographic research vessel uses sonar to map the depth of the seabed.
Sound waves are emitted downwards from the vessel. Some of these waves are reflected by the seabed and detected back at the vessel.
The shortest time between the sound waves being emitted and detected is 0.12 s0.12\text{ s}0.12 s.
The speed of sound in seawater is 1.5 km/s1.5\text{ km/s}1.5 km/s.
Calculate the distance from the vessel to the nearest point on the seabed.
Each sound wave pulse is emitted for a very short duration.
The reflected sound wave received back at the vessel lasts for a longer duration.
Suggest a reason for this difference in duration.
30 exam-style questions on Edexcel IGCSE Physics Light and sound. Each one has a worked solution and a mark scheme showing where the marks go.