A loudspeaker emits sound towards the open end of a pipe. The other end is closed. A standing wave is formed in the pipe. The diagram represents the displacement of molecules of air in the pipe at an instant of time. 1a. Outline how the standing wave is formed. {1 mark} x and Y represent the equilibrium positions of two air molecules in the pipe. The arrow represents the velocity of the molecule at Y. 1!). Draw an arrow on the diagram to represent the direction of motion of {I mark} the molecule at x. 1:. Label a position N that is a node of the standing wave. {1 mark} 1d. The speed of sound is 340 m 5'1 and the length of the pipe is 0.30 [2 marks] m. Calculate, In Hz. the frequency of the sound