Q14. The length of a guitar's strings is 650 mm. What is therefore the wavelength of a wave on any of the strings if the string is free to move?

Q15. Using your answers from Q11 and Q14, calculate the wave speed on the A4 string of a guitar. What is the wave speed on the A3 string of a guitar?

Q16. You hear your brother playing the guitar in his room at the end of the hall way, 8 m away from you. How long does the sound take to travel from his guitar to your ear?

Q17. Does the amplitude of a wave change its frequency?

Q18. What is the speed of sound in sea water? Whales and dolphins use sound to communicate under water. What are the frequency and the wavelength of the musical note A5 in sea water.

Q19. Find out what ultra-sound is. What are applications of ultra-sound?