1. SMDEP Physics Oscillations, Waves Any trumpet players in the house? Please see me after class today. Webpage updated: http://www.astro.yale.edu/krines/smdep

2. Quiz Results Pre-quiz and Post-quiz to measure change Pre-quiz mean: 8.6 (max:24) Post-quiz mean: 15.7 (max:29) –This change is larger than most semester- long, lecture-based courses –You all did it in 11 days! Individual Pre/Post scores available at end of class

3. Ch 15, #2: AM radio wavelength? 1.200-550 km 2.200-550 m 3.20-55 m 4.2-5.5 mm 5.Other 6.Didn’t finish

4. Ch 15, #2b: FM radio wavelength? 1.2.8-3.4 km 2.0.29-0.36 m 3.28-34 m 4.2.8-3.4 m 5.Other 6.Didn’t finish

5. Ch 15, #12: ratio of amplitudes? 1.2 2.2 1/2 3.4 4.8 1/2 5.Other 6.Didn’t finish

6. A mass attached to a spring oscillates back and forth as indicated in the position vs time graph below. At point P the mass has: t x P 1.Positive velocity and positive acceleration 2.Positive velocity and negative acceleration 3.Positive velocity and zero acceleration 4.Negative velocity and positive acceleration 5.Negative velocity and negative acceleration

7. The picture below is a top view of ripple waves made by a water bug moving on the surface of a lake. From the wave pattern, we can see that the bug has been moving: 1.Continuously to the left 2.Continuously to the right 3.Back and forth, first right then left 4.Back and forth, first left then right 5.In a circle

8. If the frequency of a wave in a medium is increased, how does the velocity of the wave change? 1.It increases 2.It decreases 3.It stays the same