Physics (AS & A Level) · Oct / Nov 2025 · Paper 13 · Question 25

A source emits a progressive sound wave in the horizontal direction. The wave travels away from the source in a direction towards the right. The graph shows the variation of the displacement of the particles from their equilibrium positions with distance from the source at a particular instant in time. Displacements to the right of the equilibrium positions are shown as positive. [graph of displacement against distance showing a sinusoidal wave with point Y on the negative displacement part] Position Y represents the displacement of a particle in the sound wave at a particular distance from the source at this instant. Which statement about the motion of this particle is correct?

1. AThe particle is moving away from the source.
2. BThe particle is moving towards the source.
3. CThe particle is moving upwards.
4. DThe particle is moving downwards.

As printed in the paper