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Exploring Music Science: Friction & Strings in Motion

Dive into the physics of music with topics like static and sliding friction on violin strings, oscillations in guitar strings, and the science behind tones. Learn from the concepts of Helmholtz and explore modern tools like oscilloscopes and signal generators.

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Exploring Music Science: Friction & Strings in Motion

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  1. Set - 5 Finishing Chapter 3 and moving on to a music science diversion

  2. Hojadu?

  3. How DID you do??(We will ask again after the grades are back) • I did great • I did OK • Not so good • Bad • Very bad

  4. How do you get your grade? • The cards must be processed. • The data will be downloaded to myUCF site. • NOT WebCT • NOT Blackboard • I may upload them to WebAssign as well. They have a gradebook function. • Probably about a week. Maybe already there!

  5. What Happens Now?? • We will complete some issues from Set-4 • We move on to the first serious topics in the physical science of music. • Later we will return to the world of physics to pick up some more background. • Next week, as soon as I get them, I will review the exam and will post a concept list by question so you can know what concepts you need to review. Or not!

  6. Let’s talk more about friction. Stationary Both forces the same Stationary – Pushing harder. Both the same. Moving Push bigger than frictional force.

  7. Graph Stationary Friction Newtons Moving Force Newtons

  8. Applied force W f N

  9. Frictional Force Stationary Sliding Applied Force

  10. Friction

  11. Which coefficient of friction is the largest? • Static • Dynamic • They are both the same.

  12. The Violin – Friction in Motion!

  13. The Bow Horsehair

  14. The Bowing Process of a Violin Performer pushes down And to the right Motion of Bow Frictional Force Reaction Force String on Bow Focus in on the relative motion of the bow and the string

  15. The Process Static Motion String moves with bow Still Static Friction about to change to sliding friction Sliding friction. The string slips back due to inertia until the string pressure goes in the other direction Process repeats

  16. Application ?? Physics Later

  17. Things that go back and forth Guitar Strings • Pendulum • Mass on Spring

  18. The Spring

  19. Spring Force Equatiom • F=-kx • The “-” sign indicates that the force and the displacement are in opposite directions.

  20. Springs Oscillate

  21. Graph

  22. Important Result for a Spring:

  23. So ….

  24. A string is just a spring misspelled!

  25. Concept … Tension

  26. Force = F The Musical String Linitial T x T T The Bigger the angle the more T points UP! The distance “x” is the same sort of thing as the x in F=-kx. ANGLE Like a spring!

  27. 1.5 1 0.5 disturbance 0 Height 0 5 10 15 20 25 -0.5 -1 -1.5 Time (seconds) Spring /String Motion

  28. The Guitar Strings

  29. Stringed Instruments PLUCK Momentum

  30. Important Definitions The PERIOD, T is the time it takes to go from one condition to the next time that exact condition is repeated. The frequency, the number of oscillations per second, is given by: Example: If T=2 seconds F=1/2 (sec-1)=0.5 per second

  31. Question What is a tone and how do you prove it??

  32. Remember Helmholtz • In physiology and physiological psychology, • he is known for his mathematics of the eye, • theories of vision, • ideas on the visual perception of space, • color vision research, • the sensation of tone, • perception of sound. • In physics, he is known for his theories on the conservation of force, • work in electrodynamics, chemical thermodynamics, • A mechanical foundation of thermodynamics. 1821 - 1894

  33. Helmholtz  Today The SINE curve

  34. Two Fuzzy Sine Waves

  35. We Know (And will know even more later) Tone

  36. Today’s Approach

  37. Speaker

  38. Into the air … Credit: http://www.soundonmind.com/

  39. Helmholtz’s Results

  40. We can study these tones with electronics Tone Or:

  41. Oscilloscope http://commons.wikimedia.org/wiki/Main_Page

  42. One More Tool Tone Signal Generator Electrical

  43. In using these modern tools • We postpone understanding how some of these tools work until later in the semester. • We must develop some kind of strategy to convince us that this approach is appropriate.

  44. The Spring

  45. Spring Force Equatiom • F=-kx • The “-” sign indicates that the force and the displacement are in opposite directions.

  46. Springs Oscillate

  47. Graph

  48. Important Result for a Spring:

  49. So ….

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