1. Find the fundamental frequency and third harmonic of an organ pipe of length 50cm. Assume the organ pipe is closed at one end and the speed of sound in air is 330ms -1 Do now: Hātarei, 16 Haratua 2015

2. New animations on moodle Clarinet – flute clip (2 min) Harmonics on a guitar (2 min) 3D mid-air acoustic standing waves (2 min) Cool stuff:

3. Read and make notes p69-72: Why does the same note sound different on different instruments? What factors determine the pitch on a guitar string? What are beats? Finish Activity 5A, start 5B Today’s Plan:

4. A guitar string of length 80cm is tuned to the musical note A which has a (fundamental) frequency of 220Hz. a) Calculate the speed of the wave along the guitar string Do now: Hātarei, 16 Haratua 2015 A different note is then played by placing your finger half-way along the string. b)Calculate the frequency of the new note

5. Halving the length produces a wave of twice the frequency – this is one octave