(a) For the arrangement shown in Figure suggest why it is easier to determine accurately the position of a node rather than an antinode.

A stationary sound wave is established between the loudspeaker and the board.

(b) Explain why it is better to measure the distance across several nodes.

For sound waves of frequency $2500 \mathrm{Hz}$, it is found that two nodes are separated by $20 \mathrm{cm}$, with three antinodes between them.

(a) Determine the wavelength of these sound waves.

For sound waves of frequency $2500 \mathrm{Hz}$, it is found that two nodes are separated by $20 \mathrm{cm}$, with three antinodes between them.

(b) Use the wave equation $v=f\lambda$ to determine the speed of sound in air.

Which statement is not correct about stationary waves?

A string is fixed between points X and Y.

A stationary wave pattern is formed on the stretched string.

The distance between X and Y is 78.0cm. The string vibrates at a frequency of 120Hz.

What is the speed of the progressive wave on the string?

(A) $11.7\mathrm{m} {\mathrm{s}}^{-1}$

(B) $23.4\mathrm{m} {\mathrm{s}}^{-1}$

(C) $46.8\mathrm{m} {\mathrm{s}}^{-1}$

(D) $93.6\mathrm{m} {\mathrm{s}}^{-1}$

This diagram shows a stationary wave on a string.

(a) On a copy of the diagram, label one node (N) and one antinode (A).

This diagram shows a stationary wave on a string.

(b) Mark on your diagram the wavelength of the progressive wave and label it $\lambda$.