Define what is meant by the wavelength of a progressive wave.
State the meaning of an antinode in a stationary wave.
A loudspeaker emitting sound at constant frequency is positioned close to the open end of a pipe, as shown in Fig. 4.1. A movable piston is a distance $x$ from the open end of the pipe. The value of $x$ is increased from $x = 0$ by moving the piston to the left at a steady speed of $0.75\,\text{cm s}^{-1}$. The speed of sound in the pipe is $340\,\text{m s}^{-1}$. A much louder sound is heard for the first time when $x = 4.5\,\text{cm}$. Assume that there is an antinode of a stationary wave at the open end of the pipe. Determine the frequency of the sound in the pipe.
After a certain time, a second much louder sound is heard. Calculate the interval of time between the first much louder sound and the second much louder sound being heard.