1. Music, Math, and Motion Dr. E.J. Zita The Evergreen St. College Winter week 4 Friday 30 Jan. 2009

2. Ch.11: Waves, continued Where to find solutions to HW online Overview of 11# 9, 10, 12, 13 Discuss sections Choose homework together, due next Friday Looking ahead

3. Giancoli solutions on Moodle

4. Review of Ch.11.9: Energy transported by waves Intensity = Power (W) / Area (m 2 ) and Power (W) = Energy (J) / time (s) so Intensity = (is matter transported?

5. Overview of 11# 10, 11, 12, 13 11.10: Intensity related to amplitude and frequency 11.11: Reflection and transmission of waves 11.12: Interference & Superposition 11.13: Standing waves & Resonance

6. Overview of 11.10: Intensity related to amplitude and frequency Total energy of simple harmonic oscillator = maximum potential energy E = ½ kA 2 Where  =  k/m = 2  f, therefore k = and E = Mass = density * volume: m =  V, volume = area * length: V = S L, and the length is the distance the wave at velocity v travels in a time t: L = v t. Therefore m = Substitute this into your result for E = Then Power = Energy / time: P = E / t = Finally, Intensity = Power / area: I = P/S = How does Intensity depend on the Amplitude and frequency of a wave?

7. Overview of 11.11: Reflection & Transmission of waves Try the PhET workshop on “Wave Interference” with ONE DRIP. Explore the similarities between this wave propagation and that described in Fig.11-34.a

8. Overview of 11.12: Interference and superposition Try the PhET workshop on “Wave Interference” with TWO DRIPS and a WALL at the far end. Explore the similarities between this wave propagation and those described in Figs.11-35 and 11-36

9. Overview of 11.13: Standing waves and resonance How can you find the relationship between the length L of the string and the wavelength  of each mode? Look at the 2-drip PhET experiment with a wall – can you detect standing waves?

10. Jigsaw learning-through-discussion 1. Count off by 10, 11, 12, 13 Each team discuss your section Identify key points Zita will circulate, answering questions 2. Mix teams so there is one expert for each chapter on each team Discuss all sections – share your key points 3. Whole group gather: resolve questions, share insights and examples, and choose homework together

11. Let’s try some HW together – you choose which

12. HW Ch.11-12

13. Extra problems More interesting problems start on p.320

14. Hints 67.  x = vt 71. KE 1 + PI 1 = KE 2 + PE 2 72. v= f 77. f n = nf 1 (n>1) 79. v max =  A 80: a max =  2 A < g

15. Looking ahead TODAY

16. HW Problems Due not next week, but the following week. Some people will have midquarter conferences next Thursday, And everyone will perform Group Project 1 next Friday.