19. What type of wave is a sound wave? 20. Waves are sent from a wave generator along a spring of fixed length. Can the speed of the wave in the spring be changed? If so, how? Can the frequency of the wave be changed? If so, how? 21. The diagram on the right shows a wave at a particular moment. in time as it travels along a rope in the direction shown. What is true about the point P on the rope? I 22. A standing wave is generated on a string which is fixed at both ends, and vibrates at its fundamental frequency. The tension of the string is now increased and a new standing wave vibrating at its fundamental frequency is generated. Which properties of the wave changed? y 23. Two sinusoidal waves travel in the same medium but one with twice the wavelength of the other. What is true of their velocities? frequencies? x 24. One violin creates a sound whose relative intensity is 58 dB. Calculate the relative intensity of 60 violins each playing at this intensity.