CAPE Physics Unit 1 · 2010 · Paper 1 · Question Q21

Sound waves with a frequency of 200\text{ Hz} travel through a medium with a speed of 400\text{ m s}^{-1}. What is the phase difference between two points which are 3\text{ m} apart in the direction of the wave?

1. (A)\frac{\pi}{4}\text{ rads}
2. (B)\frac{\pi}{2}\text{ rads}
3. (C)\frac{2}{3}\pi\text{ rads}
4. (D)\pi\text{ rads}