A longitudinal wave of frequency 400 Hz travels through a medium. The wave speed is 320 m s-1.
Which statement describes the motion of a particle in the wave?
It is travelling at a speed of 320 m s−1320\text{ m s}^{-1}320 m s−1.
It moves in phase with a particle in the wave 40 cm40\text{ cm}40 cm away.
It oscillates with a time period of 2.5 ms2.5\text{ ms}2.5 ms.
It changes direction 400 times every second400\text{ times every second}400 times every second.