1. SMDEP Physics Waves, Superposition, Standing Waves 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! Office Hours M, Tu 5-7 pm –Answer sheets available, blank quiz for inspection

3. Ch 15, #31(a): ratio v 2 /v 1 of speeds of waves 1.(  1 /  2 ) 1/2 2.(  2 /  1 ) 1/2  2 /  1  1 /  2 5.Other 6.Didn’t finish 0 of 5 10

4. Ch 15, #31(b): ratio of wavelengths (string 2 to string 1) 1.(  1 /  2 ) 1/2 2.(  2 /  1 ) 1/2  2 /  1  1 /  2 5.Other 6.Didn’t finish 0 of 5 10

5. Ch 15, #36: violin frequency? 1.294 Hz 2.74 Hz 3.221 Hz 4.392 Hz 5.Other 6.Didn’t finish 0 of 5 10

6. Ch 15, #44 abc: mass for 1/2/5 loops? 1.(1.38, 0.35, 0.055) kg 2.(2.76, 0.7, 0.1) kg 3.(0.38, 0.09, 0.011) kg 4.(1.38, 5.5, 35) kg 5.Other 6.Didn’t finish 0 of 5 10

7. Consider a wave, described by y=y m sin(kx+  t). What is the motion of a particular location (a particular x value) along the string? 10 0 of 70 1.Back and forth in the +/- x direction 2.Back and forth in the +/- y direction 3.Back and forth in the +/- z direction 4.Cannot tell without more information

8. Consider the same wave, described by y=y m sin(kx+  t). What is the shape of the wave? 10 0 of 70 1.Sine function 2.Sine function plus linear term 3.Cannot tell without more information

9. Consider the same wave, described by y=y m sin(kx+  t). What is the velocity of propagation of the wave? 10 0 of 70 1.  /k 2.k/  3.dy m /dt 4.Cannot tell without knowing the properties of the string

10. Consider the same wave, described by y=y m sin(kx+  t). What direction is the wave traveling? 10 0 of 70 1.In the +x direction 2.In the –x direction 3.In the +y direction 4.In the –y direction 5.Cannot tell without knowing the properties of the string

11. Consider the sum of two identical waves (same amplitude, wavelength, frequency, phase, propagation direction). What is the amplitude of the sum? 10 0 of 70 1.Same as either wave 2.Twice the amplitude of either wave 3.Half the amplitude of either wave 4.Zero 5.None of the above

12. Consider the sum of two similar waves (same amplitude, wavelength, frequency, propagation direction), but with phase different by  radians. What is the amplitude of the sum? 10 0 of 70 1.Same as either wave 2.Twice the amplitude of either wave 3.Half the amplitude of either wave 4.Zero 5.None of the above

13. Consider the sum of two similar waves (same amplitude, wavelength, frequency, propagation direction), but with phase different by 2  radians. What is the amplitude of the sum? 10 0 of 70 1.Same as either wave 2.Twice the amplitude of either wave 3.Half the amplitude of either wave 4.Zero 5.None of the above

14. Consider the sum of two similar waves (same amplitude, wavelength, frequency, propagation direction), but with phase different by  radians. What is the amplitude of the sum? 10 0 of 70 1.Same as either wave 2.Twice the amplitude of either wave 3.Half the amplitude of either wave 4.Zero 5.None of the above